Bridge Group bridge practice guidelines

Arizona Department of Transportation
SECTION 1: SECTION 2: SECTION 3: SECTION 4: SECTION 5: SECTION 6: SECTION 7: SECTION 8: SECTION 9: SECTION 10: SECTION 11: SECTION 12: SECTION 13: SECTION 14: SECTION 15: SECTION 16:
GENERAL GENERAL DESIGN AND LOCATION FEATURES LOAD AND LOAD FACTORS STRUCTURAL ANALYSIS AND DESIGN METHODS CONCRETE STRUCTURES STEEL STRUCTURES ALUMINUM STRUCTURES WOOD STRUCTURES DECKS AND DECK SYSTEM FOUNDATIONS AND SUBSTRUCTURES RETAINING WALLS AND SOUND BARRIER WALLS CULVERTS AND BURIED STRUCTURES RAILINGS JOINTS AND BEARINGS TRAFFIC STRUCTURES BRIDGE CONSTRUCTION
Arizona Department of Transportation
Bridge Group
SECTION 1- GENERAL
Chapter PURPOSE � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � STRUCTURE IDENTIFICATION � � � � � � � � � � � � � � � � � � � � � � � � Bridge Definition � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Structure Name � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Structure Number � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Station� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Route and Milepost � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � BRIDGE DESIGN PHASES � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � General � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Initial Design � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 1 � Initial Bridge Study Title Sheet � � � � � � � � � � � Figure 2 � Initial Bridge Study Report Body � � � � � � � � � Figure 3 � Initial Bridge Study Concept Sketch � � � � � � � Preliminary Design � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Preliminary Bridge Selection Report � � � � � � � � � � � � Bridge Over Waterways� � � � � � � � � � � � � � � � � � � � � � � Widenings/Rehabilitation � � � � � � � � � � � � � � � � � � � � � Approval � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Bridge Selection Report � � � � � � � � � � � � � � � � � � � � � � � FHWA Approval� � � � � � � � � � � � � � � � � � � � � � � � � � � � � Final Design � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Stage III� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Stage IV � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � PS & E Submittal � Stage V � � � � � � � � � � � � � � � � � � � Bid Advertisement Date � � � � � � � � � � � � � � � � � � � � � � � � � � Bid Opening � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Post Design Services � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � BRIDGE PROJECT ENGINEER'S RESPONSIBILITY � � � General � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Page 3 3 3 3 4 4 5 5 5 5 8 9 10 11 11 12 12 13 13 13 13 14 14 14 14 14 14 15 15 Issue Date 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01
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Selection of Bridge Project Engineers� � � � � � � � � � � � � � � � Duties of Bridge Project Engineers � � � � � � � � � � � � � � � � � � � � CONSULTANT REVIEW PROCEDURES � � � � � � � � � � � � � � � � General � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Documentation � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Reviews � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 30% Submittal � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 60% Submittal � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 95% Submittal � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 100% Submittal� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Project Review � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � COMPUTING APPROXIMATE QUANTITIES � � � � � � � � � � � General Guidelines � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 1 - Approximate Quantities � � � � � � � � � � � � � � � � � � Table 2 - Sample Approximate Quantities for Concrete Reinforcing Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 3 - Weights in lbs of Deformed Reinforcing Bars Table 4 - Weights of � " Spirals per Vertical Foot � � � � � Structural Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 5 - Sample Approximate Quantities for Reinforcing Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 6 � Sample Approximate Quantities for Structural Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Inclusion List for Structural Steel � � � � � � � � � � � � � � � � � � Table 7 � Structural Steel Plate Weight Increase � � � � � � Table 8 � Weight of Stud Shear Connectors � � � � � � � � � � Table 9 � Weights in lbs of Welds per Linear Foot (45O fillet weld) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Exclusion List for Structural Steel � � � � � � � � � � � � � � � � � � Structural Steel (Miscellaneous) � � � � � � � � � � � � � � � � � � � � Structural Excavation � � � � � � � � � � � � � � � � � � � � � � � � � � � � Structure Backfill � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 10 � Structural Excavation Payment Limit � � � � � Figure 11 � Structure Backfill Payment Limit � � � � � � � � Drilled Shafts � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Driven Piles � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 12 � Length of Piling � � � � � � � � � � � � � � � � � � � � � � � Precast Prestressed Concrete Members � � � � � � � � � � � � � � Miscellaneous Items � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �
15 16 17 17 17 18 18 18 19 19 19 20 20 20 21 22 23 24 24 25 26 27 28 28 28 29 29 29 30 30 32 33 34 35 36 37 38
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PURPOSE
The purpose of these Guidelines is to document ADOT Bridge Group design criteria and to provide guidance on interpretations of the various AASHTO publications and other documents as related to highway bridges and appurtenant structures. The Guidelines are intended to be used for general direction. It will continue to be the responsibility of the designer to ensure that these guidelines are applied properly and modified where appropriate with the necessary approvals. The guidelines should be used with judgment to ensure that the unique aspects of each particular design are properly considered.
STRUCTURE IDENTIFICATION
The procedures for structure identification are established by the National Bridge Inspection Standards. Refer to the Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation's Bridges prepared by FHWA and the Arizona Structure Inventory prepared by ADOT Bridge Management Section.
Bridge Definition
"A 'bridge' is defined as a structure including supports erected over a depression or an obstruction, as water, highway or railway and having a track or passageway for carrying traffic or other moving loads and having an opening measured along the center of the roadway of more than 20 feet between undercopings of abutments or springlines of arches or extreme ends of openings for multiple boxes; it may include multiple pipes, where the clear distance between openings is less than half of the smaller contiguous opening."
Structure Name
Names of State bridges are assigned by the Bridge Management Section Leader. Structures are named in accordance with the kind of facility that goes under or over the principal route. A traffic interchange structure will have "T.I." as part of the name. Overpasses carrying one-way traffic will also include the direction of traffic as part of the name. The name is limited to a 20 digit field. Term Bridge Overpass Underpass Traffic Interchange (T.I.) Description The term "bridge" is usually reserved for structures over water courses or canyons. A structure carrying the principal route over a highway, street or railroad. A structure which provides for passage of the principal route under a highway, street, railroad or other feature. An overpass or underpass is also called a T.I. if on and
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Viaduct Tunnel Pedestrian Overpass Pedestrian Underpass
off ramps are provided to the intersecting roadway. A structure of some length carrying a roadway over various features such as streets, waterways or railroads. A structure carrying a roadway through a hill or mountain. A structure carrying a pedestrian walkway over a roadway. A structure which provides for passage of a pedestrian walkway under a roadway.
Structure Number
Each defined 'bridge' has a unique number assigned by the Bridge Management Section according to the group of numbers allotted to each maintenance responsibility. Twin or parallel structures are numbered individually if there is an open median. Structure number identification remains unique and permanent to that structure. The structure number will be retired only for structures totally removed, for one of two twin structures where the median is closed by subsequent construction or for transfer between state and local agency jurisdiction. The structure numbers allotted to each maintenance responsibility category are as follows: Structure Number 0001-2999 3000-3999 4000-7999 8000 and above Maintenance Responsibility Category State jurisdiction bridges Federal jurisdiction bridges State jurisdiction culverts Local jurisdiction bridges and culverts
Station (Principal Route)
The station identification of the structure is located along a construction centerline of the principal route on or under the structure as determined from the State Highway System Log. For overpass structures with the principal route on the structure, the beginning bridge station is used which is located at the backwall of abutment 1. For underpass structures with the principal route under the structure, use the station of the point of intersection between the principal route under and the construction centerline on the structure. For culvert structures, under 20 feet use the station of the point of intersection between the principal route and the construction centerline of the culvert. For culvert structures 20 feet and over, use the station of the beginning backwall.
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Route and Milepost
The principal route and milepost identification shall be shown on all plan sheets. The milepost of the route on or under the structure is determined from the Arizona Highway System Milepost Log. The milepost is recorded to the nearest 1/100th of a mile as calculated from the Station (Principal Route).
BRIDGE DESIGN PHASES General
The design of a major structure consists of three design phases: Initial Design, Preliminary Design and Final Design. The Initial Design Phase consists of examination of bridge concepts including type, length and depth. These studies may be prepared prior to submitting a project in the 5 Year Program or in conjunction with the preparation of a Project Assessment (PA) or a Design Concept Report (DCR). These studies will form the basis for the Bridge Selection Report and provide the Geotechnical Engineer with sufficient information to order one or two initial borings to be used in providing a preliminary foundation recommendation. The Preliminary Design Phase consists of two distinct activities. The first activity is the Alternatives and Selection Study Phase where different bridge types with varying span lengths, girder spacings and foundation types are investigated along with other structure types and comparative cost estimates. This activity results in a Preliminary Bridge Selection Report which will be distributed for comments and provide the Geotechnical Engineer with the required information to perform a final drilling program and produce a Bridge Geotechnical Report. The second activity consists of finalizing the Bridge Selection Report based on the final Bridge Hydraulics Report and Bridge Geotechnical Report. The Final Design Phase consists of performing the required design calculations, drawing the plan sheets, preparing a final estimate and preparing the Special Provisions for bridge related items.
Initial Design
The Initial Design Phase consists of developing an Initial Bridge Study. The purpose of the Initial Bridge Study is to: � � Provide the structure depth for setting profile grades. Establish the best possible early cost estimate.
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Allow for Bridge Group input in scoping activity. Familiarize Bridge Design with upcoming projects. Describe and document the design assumptions used in the development stage. Document the existing bridge condition, including waterway adequacy if appropriate, for bridge replacement projects.
Up to three studies could be made during this phase; one as a study to determine a project's merits prior to becoming a project to be included in the 5 Year Program, one as for development of the Project Assessment and one as information for development of a Design Concept Report. The purpose of these studies is to develop as early as possible a feasible type of structure, cost and design restrictions for each site. The completeness of the study will depend on when the study is performed. For example, a study for a Design Concept Report should have more information than a pre-programmed study. Each of the three possible study times should be viewed as part of a continuous effort to define the scope of the project with each new study building on the previous study. An Initial Bridge Study will be performed for all major bridge projects to be nominated to the 5 Year Program by the Bridge Group or the Districts prior to nomination. For existing bridges, this study will be performed in conjunction with the Bridge Candidate List for the Highway Bridge Replacement and Rehabilitation Program to help determine which candidate bridges should be programmed for replacement. Close coordination with Bridge Management Section, Drainage Section and the Districts will be required. These studies will examine the condition of qualified existing bridges to determine which bridges should be developed into replacement projects. An Initial Bridge Study will be performed for all major structures during the Project Assessment Stage. If a study has already been performed, the original study should be updated and enhanced based on whatever additional data has become available. The project manager will initiate the process and establish the schedule for this activity. When concensus can not be reached at the Project Assessment Stage, the project will require a Design Concept Report. Previous studies should be used as a basis for a new Initial Bridge Study; however, additional alignments will be investigated requiring additional studies of alternates. On projects involving rehabilitation or replacement of existing bridges, the project manager shall identify the historical significance of the bridge before concept studies are initiated. The historical significance is determined from the Arizona Structure Inventory and involves a variety of characteristics: the bridge may be a particularly unique example of the history of engineering; the crossing itself might be significant; the bridge might be associated with a historical property or area; or historical significance could be derived
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from the fact the bridge was associated with significant events or circumstances. A copy of the Arizona Structure Inventory is on file. For projects where existing bridges are involved, a thorough review of the Bridge Inspection File and coordination with Bridge Management Section will be required. The major study emphasis will be to verify the condition of the existing bridge, to develop concepts for replacement including the feasibility of widening or rehabilitating versus replacement, and to determine project costs. At this stage, bridge costs will be based on square foot of deck. These Initial Bridge Studies are concepts based on the best available information and are subject to change. Assumptions used as the basis for these studies should be clearly documented and items that are likely to be subject to change as more information is obtained should be identified. An Initial Bridge Study will consist of a title sheet, report body and concept sketch. Refer to figures 1,2 and 3 for a sample of format and contents.
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FIGURE 1 INITIAL BRIDGE STUDY TITLE SHEET
ARIZONA DEPARTMENT OF TRANSPORTATION BRIDGE GROUP BRIDGE DESIGN SECTION A, B or C
INITIAL BRIDGE STUDY DATE
HIGHWAY NAME PROJECT NAME PROJECT NUMBER TRACS NUMBER
BRIDGE NAME EXISTING STRUCTURE NUMBER MILEPOST
Prepared by
Date
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FIGURE 2 INITIAL BRIDGE STUDY REPORT BODY
GENERAL: This section should contain a general discussion of the project including location of the bridge and purpose of the study. EXISTING ROADWAY: This section should contain a discussion of the existing roadway geometrics including identification of any deficiencies. EXISTING DRAINAGE: This section should contain a discussion of the hydrology and hydraulics of the site including design Q, high water, capacity, bank protection and scour vulnerability of existing bridge. EXISTING BRIDGE: This section should contain a discussion of the bridge geometrics and condition of the existing bridge including: rating of the deck and superstructure, adequacy of existing bridge rail, whether bridge is designed for a future wearing surface, the seismic vulnerability, condition of the bearings, expansion joints and approach slabs and a recommendation on whether the bridge could be widened or rehabilitated. ALTERNATES: This section should contain a discussion of the various alternates investigated including: structure type, superstructure depth, girder spacing, column type and spacing, foundation alternates, construction phasing, traffic handling and costs.
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FIGURE 3 INITIAL BRIDGE STUDY CONCEPT SKETCH
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Preliminary Design
Preliminary design consists of three distinct activities: (1) performing concept studies and producing a Preliminary Bridge Selection Report, (2) development of preliminary plans for the chosen alternate and finalizing the Bridge Selection Report and (3) obtaining FHWA approval of the Bridge Selection Report.
Preliminary Bridge Selection Report
The Preliminary Bridge Selection Report consists of performing concept studies as a continuation of the Initial Bridge Study. These studies involve investigating alternate superstructure and foundation types including variations of span length, structure depth and number of girders to determine the best bridge type and arrangement for a particular site. This portion of the Preliminary Design Phase is an iterative phase where assumptions must be made and later verified or modified during the process. Detailed indepth design should not be performed in this phase unless it is necessary to confirm the adequacy of the concept. When performing the concept studies the following shall be considered as a minimum: � � � � Cost Constructability Maintenance Aesthetics
Sketches should be made of the various alternates. During this phase, both the vertical and horizontal clearances should be checked to ensure that the adequate clearances are provided. Inadequate vertical clearance will necessitate a change in either profile grade or superstructure depth while inadequate horizontal clearance may necessitate a change in span length. During this phase, the geotechnical aspects of the site should be considered since the foundation type and associated cost may influence the type of bridge selected. Since a preliminary drilling program has been performed following the Initial Design Phase, a preliminary Bridge Geotechnical Report will be available for use in determining foundation type and costs. During this phase, the traffic requirements must be investigated including any detours or phasing requirements. These details should be worked out with Traffic Design. The need for a deck protection system and type of system will be determined during this phase. Details of the system should be worked out with Bridge Management Section.
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Bridges over Waterways
For waterway crossings, the Preliminary Design Phase will require coordination with Drainage Section or the drainage consultant, as appropriate. The designer should obtain the Bridge Hydraulics Report and thoroughly review the contents before starting the concept study phase.
Widenings/Rehabilitation
On projects involving widenings, in addition to the requirements for new bridges, the following items should be investigated during the Preliminary Design Phase: � Comments from the environmental process concerning the historical significance of the structure, if any, should be added to the discussion of the historical significance contained in the Initial Bridge Study. The existing structure should be checked for structural adequacy. The main superstructure girders should be checked for adequacy to carry the appropriate design live load. If the bridge does not rate sufficiently high, the girders may need to be strengthened, respaced or replaced, or a new bridge may be recommended. The deck slab should also be checked. Decks that are severely overstressed may require replacement. The condition of the existing deck joints should be investigated. If the existing joints are not working or are inadequate, they may require replacement. The condition of the existing bearings should be investigated. If the existing bearings are not performing adequately, they may require modification or replacement. This can affect cost and traffic phasing. The condition of existing diaphragms on steel girder bridges should be investigated. The need for this or any other repair work should be determined at this time. Welded diaphragms have caused past problems. The existing foundations should be checked for adequacy against predicted scour and if inadequate, appropriate means taken to upgrade the foundations against failure. The existing waterway opening should be checked to ensure that it can properly handle the design frequency event. Assessment of scour vulnerability and condition of bank protection should be included. The need for adding approach slabs and/or anchor slabs, if missing, should be investigated. The adequacy of existing bridge rail, that would be left in place, should be investigated.
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The need for earthquake retrofit measures should be determined. Existing or proposed utility conflicts should be investigated.
When the above items have been investigated, preliminary design can proceed by studying alternatives. Possible alternatives include: widening to one side, widening symmetrically on both sides or replacing the bridge with a new structure. Approximate costs based on preliminary quantities and unit costs associated with each solution will be required.
Approval
When a decision has been reached concerning the type of bridge selected, the justification for the choice along with comparative cost estimates and sketches should be summarized in the Preliminary Bridge Selection Report. This report should be submitted to the Section Leader and State Bridge Engineer for approval. When approved, the Preliminary Bridge Selection Report should be presented to the Geotechnical Engineer for their use in conducting a final geotechnical investigation.
Bridge Selection Report
The finalization of the Bridge Selection Report is the second activity in the preliminary design phase. This activity involves incorporating the contents of the final Bridge Hydraulics Report and final Bridge Geotechnical Report into the Preliminary Bridge Selection Report to produce a final Bridge Selection Report and develop the preliminary plans for the approved alternative. The preliminary plans consist of the General Plan and the General Notes and Quantities Sheets. The preliminary plans are not considered complete until the Bridge Hydraulics Report and Bridge Geotechnical Report are received and incorporated in the plans. There may be up to a six month delay between ordering drilling and receiving a recommendation.
FHWA Approval
This activity consists of obtaining FHWA approval of the Bridge Selection Report for Federal Aid Projects. Upon receipt of FHWA approval, the Preliminary Plans are considered complete and the Final design of the bridge may start.
Final Design
The Final Design Phase consists of performing the required structural analysis for the bridge and drawing the required details for the development of the construction drawings, producing the final cost estimate and preparing the Special Provisions. This phase should not start until the preliminary documents have been approved.
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Final design consists of two phases: the first phase consists of designing and producing drawings for the Stage III document submittal, the second phase consists of completing the Stage IV final documents.
Stage III
This activity involves completion of most of the structural analysis; some of the drawings, a preliminary cost estimate with quantities and unit costs; and any required special provisions. This phase will also include reviewing the 60% project plans, submitting comments and attending the office and/or field review.
Stage IV
This activity consists of incorporating the Stage III review comments in the design, completing the structural analysis and drawings, producing final quantities and a final cost estimate, and reviewing the Special Provisions. When the project design is complete and quantities are calculated, a cost estimate shall be made. Unit costs may be obtained from the latest copy of the Unit Cost Summary and from the Bridge Group Bridge Costs Records. Unit prices should be adjusted for site location, size of project and other pertinent data.
PS & E Submittal - Stage V
The Plans, Specifications and Estimate (PS & E) Submittal is the final review of the project. This submittal shall be made when requested by the Control Desk. Complete plans and final quantities should always be finished by this date.
Bid Advertisement Date
The Bid Advertisement Date is the date the project is advertised. The Active Project Status Report refers to this date as the Bid Date. When requested by the Control Desk, the complete, signed and stamped tracings shall be sent to the Control Desk for printing of the bid sets.
Bid Opening
The Bid Opening is the date when the bids are opened. This activity normally ends the design phase. The construction contract for the project is then awarded at the next scheduled Arizona Transportation Board meeting.
Post Design Services
Post design services include the following activities: attending partnering sessions, making plan changes as a result of errors or changed conditions, approving falsework and shop drawing submittals, supervising structural steel inspections, producing as-built plans and reviewing the final as-built structural drawings for evaluation of design work and study for improvement.
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BRIDGE PROJECT ENGINEER'S RESPONSIBILITY General
Bridge Project Engineers are to be assigned to all new projects in which structure plans are required. The Bridge Engineer or Bridge Designer will be designated as the Bridge Project Engineer when the project study report or final Project Assessment becomes available and will be responsible for project delivery for all structure related items thru PS & E completion and subsequent construction contract completion. Bridge Project Engineers are hereby given the authority and will be responsible for seeing that all Bridge Group design features comprising the PS & E package on projects are delivered on time, within budget, and in conformance with standards, to meet established schedules. Such features include structure plans for bridges, earth retaining structures, hydraulic structures, highway sign and lighting support structures, specifications for structures, and cost estimates for structures. Bridge Project Engineers may also have responsibility for coordinating work efforts for completion of all work tasks if they are assigned as Project Managers according to the provisions of the Project Management process.
Selection of Bridge Project Engineers
Bridge Designers and Bridge Engineers interested in being selected as Bridge Project Engineers must obtain their Professional Engineer License and they must exhibit a majority of the following skills or traits: � � � � � � � � Has developed the technical skill. Gets along well with people. Is an innovator. Has initiative. Communicates effectively. Is practical. Has leadership abilities and will make decisions. Keeps abreast of technical developments.
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� �
Has an understanding of ADOT policies and procedures. Understands the importance of project deadlines.
Duties of Bridge Project Engineers
A Bridge Project Engineer is assigned to support or act as the Project Leader or Project Manager and to direct the specific work effort assigned to Bridge Group. The duties of the Bridge Project Engineer shall include: � � � � Remain completely knowledgeable about the specific project tasks assigned. Direct the project work activities assigned. Coordinate with the project leader or project manager, as appropriate, on schedule, budget and quality control. Provide input for establishing a project's network model and on a continuous basis, provide input to update schedule data in the Management Scheduling and Control System. Review all preliminary reports for the project. Review bridge maintenance records for widening and rehabilitation projects. Review prior commitments to other agencies and coordinate commitments with ADOT policies. Direct preparation of Bridge Selection Reports and submit for approval as required. Coordinate structural details and design features within the project. Conduct meetings with designers and detailers as required. Work closely with other groups and services so that decisions in these areas are timely and consistent throughout the project. Attend scheduled progress meetings and site visits and provide information as required. Submit structure plans, special provisions and cost estimate on schedule. Coordinate all bridge construction liaison activities such as shop drawing review, construction modifications and final as-building.
� � � � � � � � �
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CONSULTANT REVIEW PROCEDURES General
This section is intended to provide procedures to be followed by the Bridge Design Sections in their review of consultant designs. The intent of these procedures is to produce consultant designs which have the same appearance (format and content) as ADOT Bridge Group in-house designs and to promote consistency among the three Design Sections and the consultants. A Project Engineer will be assigned to each consultant review project. Large bridge projects will usually also have a designer assigned to the project to assist in the review.
Documentation
Reviews will be performed on scoping documents such as Project Assessments or Design Concept Reports whether prepared by a consultant or ADOT. Reviews will also be performed on consultant bridge designs at the 30%, 60%, 95% and 100% stages. All submittals shall be stamped with the date received and a log book of all consultant review submittals shall be kept by each Section. The log shall track the type of review document, the date each submittal is received, the date when comments are due, and the date comments are returned. An official project review file, consisting of hard grey filing folders, and a working file should be maintained for each project. The official project review file shall be organized the same as for in-house designs with a title sheet, an index and correspondence on the left side and review comments on the right side. The working file shall contain the submittal documents, special provisions and reviewer calculations. Review comments should be returned to the project manager and be submitted on a Bridge Group Comment Review Form. A copy of all review comments shall be kept in the Official Project Review File.
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Reviews
At each review stage, the reviewer should verify that all previous comments have been resolved and are properly reflected in the new submittal. When all old comments have been resolved, the old submittal documents may be discarded. Reviews should be made to ensure that each submittal meets the requirements for the appropriate submittal stage. Reviews should also verify major features of the design but should not include number by number calculation checks. Calculations will not usually be submitted unless requested by the reviewer.
30% Submittal
For a 30% submittal, the following items should be included as a minimum: � � � � � General Plan Bridge Selection Report Cost Estimate Final Bridge Geotechnical Report Final Bridge Hydraulics Report
Review of 30% submittals should be limited to ensuring that the proper bridge type, span lengths, widths and structure depth have been selected. An independent preliminary superstructure analysis should be performed to verify the structure depth. The reviewer should also check for consistency between the Geotechnical and Hydraulics Reports as related to the recommended foundation type. The General Plan and General Notes and Quantity Sheets should be complete except for the quantity box. Unit costs should be reviewed and bid items compared to the Approximate Quantity Manual guidelines.
60% Submittal
For a 60% submittal the following items should be included as a minimum: � � � � � � 60% Bridge Plans Superstructure completed Boring logs completed Substructure started Draft Bridge Special Provisions Cost Estimate including Bid Items, Item numbers and unit costs
Review of 60% submittals should consist of ensuring that major bridge items have not changed from the 30% submittal and that all 30% comments have been incorporated into the plans. The deck and superstructure designs should be checked. The superstructure plan sheets should be complete. The reviewer should verify that the substructure is consistent with the Bridge Geotechnical Report.
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95% Submittal
For a 95% submittal the following items should be included as a minimum: � � � 95% Bridge Plans Final Special Provisions Final Cost Estimate
Review of 95% submittals should consist of ensuring that 60% review comments have been incorporated into the plans. A review of the substructure for clarity and completeness should be made.
100% Submittal
The 100% submittal should be reviewed to ensure that the 95% comments have been incorporated into the plans and that all outstanding issues have been resolved.
Project Review
In addition to the review of bridge documents, the reviewer should review the project plans for consistency between the bridge plans and the civil and traffic plans. Items such as roadway profiles, bearings and width should be reviewed. Other items which should be reviewed include the appropriate use of Standard Drawings including such design features as CBCs, retaining walls, pipe headwalls and tubular sign supports. Items involving special design should be given oversight review. Such items might include light poles, sign supports, tubular signs, FMS, retaining walls, CBCs, miscellaneous structural items, sound walls and Barrier Summary Sheets.
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COMPUTING APPROXIMATE QUANTITIES General Guidelines
The Purpose of this section is to establish guidelines and methods for the computation of approximate quantities for bridges and related structures and to identify the proper Bid Item Numbers. Quantities are used in the preparation of the Engineer's estimates and in establishing bid schedules. Contractors use the quantities as a basis for making contract bids. Box Culvert quantities are to be computed in accordance with the Reinforced Concrete Box Culvert Manual. Sample approximate quantities sheets, Table 1, are provided to show the accuracy required for calculations. A second set of computations for each structure should be made by a checker independently of the original calculations. This rigorous check is needed to minimize error and prevent the omission of a major item. Small sketches of the items being calculated should be shown on the calculation sheets when the item description is not completely self-explanatory. The effort made to keep the calculation sheets easy to follow will be invaluable during back-checking. This section identifies commonly used Standard Bid Items with Descriptions, Materials, Construction Requirements, Methods of Measurements and Basis of Payments in accordance with ADOT Standard Specifications. If a new Bid Item is required, a Special Provision will have to be written. Contracts and Specifications Section should be contacted for the proper number to be used. If the structure drawings do not give enough information to compute the quantities, it is evident they are deficient and should be revised.
Concrete
The total figure of each item entered in the approximate quantities table as superstructure, pier or abutment is to be rounded to the nearest C.Y. The degree of accuracy required in deriving this total is outlined on Table 2, titled "Sample Approximate Quantities for Concrete". In cases where the designer has used more than one class or strength of concrete, caution should be exercised so that each part of the item figured is grouped in the proper class and strength of concrete.
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TABLE 1 APPROXIMATE QUANTITIES
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TABLE 2 SAMPLE APPROXIMATE QUANTITIES FOR CONCRETE ARIZONA DEPARTMENT OF TRANSPORTATION
APPROXIMATE QUANTITIES TRACS NO.: STATION PROJ. NO.: CLASS "S" f'c = psi STRUCT. BKFL. STRUCTURE NAME NB/EB
SHEET 1 OF 3 DATE: 3-15-2001 SB/WB BY ABC CHKD DEF OTHER: STRUCTURAL EXCAVATION
FOR: Superstructure-Class `S' Concrete
ITEM DESCRIPTION Class "S" f'c=3000 Parapet "A" Curb "B" UNIT DEPTH
(ft)
UNIT WIDTH
(ft)
UNIT LENGTH
(ft)
NO OF UNITS
(PER ITEM)
TOTAL
CU. FT REVISION
1.500 0.750
0.920 1.250
160.000 160.000
1 1
2 2
442 300 742 / 27=27 c. y.
Class "S" f'c=4500 Deck "C" Girders-Inter. "D" Girders-ends "D" Diaph. @abut. "E" Diaph.-Inter. "E"
0.542 3.167 3.167 2.250 2.167
41.333 1.167 1.167 1.292 0.833
160.000 48.000 25.080 37.170 4.830
1 7 7 1 6 ROUND TO NEAREST CUBIC FOOT.
1 2 2 2 2
3,584 2,484 1,298 216 105 7,687 / 27 c. y. = 285 c. y.
CARRY TO THREE DECIMAL PLACE ACCURACY.
ROUND TO NEAREST CUBIC YARD (TO BE COMPARED WITH CHECK SET).
IT IS RECOMMENDED THAT SMALL SKETCHES BE DRAWN OF PARTS BEING FIGURED.
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Bid Item Numbers for concrete quantities vary based on the specific concrete strength. If a concrete strength not shown is required, Bid Item Number 6010010 should be used. A list of Bid Item Numbers, Items and Units for various concrete strengths follows: ITEM NO. 6010001 6010002 6010003 6010004 6010005 6010006 6010007 6010010 IT E M STRUCTURAL CONCRETE (CLASS S) (F'c=2500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=3000PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=3500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=4000PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=4500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=5000PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=5500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c= ) UNIT CY CY CY CY CY CY CY CY
Reinforcing Steel
The total accumulated figure for each listed Item (Abutment, Pier, Superstructure, etc.) used for reinforcing steel in the approximate quantities table is rounded to the nearest 5 pounds. The following items are omitted from reinforcing steel weights: � � Round smooth bars or bolts. Reinforcing in piles or reinforcing extending into abutments or piers from piles or drilled shafts. For reinforcing transitioning from a drilled shaft to a column refer to Drilled Shafts Section. Reinforcement not shown on the project drawings required for anchorage zone recess blocks, duct ties and grillage assemblies as recommended by the posttensioning system used.
�
The length of each item of reinforcement not detailed on the drawings is figured to the nearest 3 inches. An amount of 2 feet is added for any lap not detailed. A lap is figured for every 40 running feet of bar. As an example, a bar required to be 90 feet in length would have a length of 4 feet added to it for 2 laps unless detailed for 46 feet or more. For lapped ends of loops, a total of 8 inches is considered adequate for all sizes of bars. Section 5, Table 1, 2 and 3 give the additional length of bar needed for end hooks on stirrups, dowels, etc. according to the size of the bars in consideration. Table 3, below, is given for the weights of standard deformed reinforcing bars.
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TABLE 3 WEIGHTS IN LBS OF DEFORMED REINFORCING BARS
SIZE W E I GHT SIZE W E I GHT #2 .167 #8 2.670 #3 .376 #9 3.400 #4 .668 #10 4.303 #5 1.043 #11 5.313 #6 1.502 #14 7.65 #7 2.044 #18 13.60
A special Table 4, shown below, is given for weight of �" diameter spiral reinforcing for round concrete columns according to the diameter, cover and pitch. TABLE 4 WEIGHTS OF �" SPIRALS PER VERTICAL FOOT
Col. Dia. (Ft.) 7'-0
Clear Cover (inches) 2 3 6 2 3 6 2 3 6 2 3 6 2
3 55.6 54.2 50.0 51.4 50.0 45.8 47.2 45.8 41.6 43.0 41.6 37.4 38.8
3� 47.7 46.5 42.9 44.1 42.9 39.3 40.5 39.3 35.7 36.9 35.7 32.1 33.3
4 41.7 40.7 37.5 38.6 37.5 34.4 35.4 34.4 31.2 32.3 31.2 28.1 29.1
4� 37.1 36.1 33.3 34.3 33.3 30.5 31.5 30.5 27.7 28.7 27.7 24.9 25.9
Pitch (inches) 5 5� 33.4 32.5 30.0 30.8 30.0 27.5 28.3 27.5 25.0 25.8 25.0 22.5 23.3 30.3 29.6 27.1 28.0 27.1 25.0 25.8 25.0 22.7 23.5 22.7 20.4 21.2
6 27.8 27.1 25.0 25.7 25.0 22.9 23.6 22.9 20.8 21.5 20.8 18.7 19.4
9 18.6 18.2 16.8 17.3 16.8 15.4 15.9 15.4 14.0 14.5 14.0 12.6 13.1
12 14.1 13.7 12.7 13.0 12.7 11.6 12.0 11.6 10.6 11.0 10.6 9.6 9.9
6'-6
6'-0
5'-6
1-24
5'-0
3 6 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6
37.4 33.2 34.6 33.2 29.0 30.4 29.0 24.8 26.2 24.8 20.6 22.0 20.6 16.4 17.8 16.4 12.2 13.6 12.2 8.0
32.1 28.5 29.7 28.5 24.9 26.1 24.9 21.3 22.5 21.3 17.7 18.9 17.7 14.1 15.3 14.1 10.5 11.7 10.5 6.9
28.1 24.9 26.0 24.9 21.8 22.8 21.8 18.6 19.7 18.6 15.5 16.5 15.5 12.3 13.4 12.3 9.2 10.2 9.2 6.0
24.9 22.2 23.1 22.2 19.4 20.3 19.4 16.6 17.5 16.6 13.8 14.7 13.8 11.0 11.9 11.0 8.2 9.1 8.2 5.4
22.5 19.9 20.8 19.9 17.4 18.3 17.4 14.9 15.7 14.9 12.4 13.2 12.4 9.9 10.7 9.9 7.3 8.2 7.3 4.8
20.4 18.1 18.9 18.1 15.8 16.6 15.8 13.5 14.3 13.5 11.3 12.0 11.3 9.0 9.7 9.0 6.7 7.4 6.7 4.4
18.7 16.6 17.3 16.6 14.5 15.2 14.5 12.4 13.1 12.4 10.3 11.0 10.3 8.2 8.9 8.2 6.1 6.8 6.1 4.0
12.6 11.3 11.7 11.3 9.9 10.4 9.9 8.6 9.0 8.6 7.2 7.6 7.2 5.9 6.3 5.9 4.6 5.0 4.6 3.5
9.6 8.6 8.9 8.6 7.6 7.9 7.6 6.6 6.9 6.6 5.6 5.9 5.6 4.6 4.9 4.6 3.7 4.0 3.7 3.0
4'-6
4'-0
3'-6
3'-0
2'-6
2'-0
Special attention is called to the sample approximate quantities for weights on Table 5, which shows the required accuracy for computation of reinforcing weights. As illustrated in the sample, a short description of the item being figured will be beneficial for comparing quantities between estimator and checker. Quantities for epoxy coated reinforcing steel shall be separated from regular reinforcing steel quantities. A list of Bid Item Numbers, Items and Units for reinforcing steel follows: ITEM NO. 6050002 6050012 ITEM REINFORCING STEEL REINFORCING STEEL (EPOXY COATED) UNIT LB LB
Structural Steel
The total figure for structural steel as entered in the approximate quantities table under the item "Superstructure" is to be rounded to the nearest 5 pounds. The degree of accuracy required in computing this total is outlined on Table 6, titled "Sample Approximate Quantities for Structural Steel".
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Structural steel weights are not figured for concrete structures; that is, structures that are dependent on reinforced or prestressed concrete slabs, girders or beams for their load carrying capacity. The cost of structural steel for these structures is included in the price bid for the concrete or other items. TABLE 5 SAMPLE APPROXIMATE QUANTITIES FOR REINFORCING STEEL
ARIZONA DEPARTMENT OF TRANSPORTATION APPROXIMATE QUANTITIES TRACS NO. STATION SHEET STRUCTURE NAME NORTHERN AVE. UP FOR UNIT WEIGHT
(PER FT)
2 OF 3
PROJ. NO.: I-10-4(24) REINF. STEEL STRUCT. STEEL ITEM DESCRIPTION Cap beam long. Back wall long. Hoops in cap Back wall verticals UNIT SIZE #5 #4 #4 #4
NB/EB SB/WB Abutment #1 NO OF UNIT
(PER ITEM)
DATE 3-15-01 . BY ABC CHKD DEF. NO OF ITEMS 1 1 1 1 Subtotal TOTAL W E IGHT 468 203 321 203 1,195 150 101 238 96 220 126 931 REVISION
UNIT LENGTH
(FT)
1.043 .668 .668 .6 6 8
40.75 38.00 13.00 4.00
11 8 37 76
Wing cap long. Hoop in wing cap Wing long. Wing long. Wing stirrups Parapet verticals
#5 #4 #5 #4 #4 #4
1.043 .668 1.043 .668 .668 .6 6 8
12.00 10.75 9.50 9.50 15.00 4.25
6 7 12 8 11 22
2 2 2 2 2 2 Subtotal
STANDARD WEIGHT FROM TABLE 4 Total ROUND TO NEAREST 3 INCHES UNLESS DETAILED ON PLANS Use 2,126 2,125 lbs.
ROUND TOTAL TO NEAREST 5 LBS.
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TABLE 6 SAMPLE APPROXIMATE QUANTITIES FOR STRUCTURAL STEEL ARIZONA DEPARTMENT OF TRANSPORTATION APPROXIMATE QUANTITIES
TRACS NO.: SHEET OF CHKD
STATION
623+ PROJ. NO. : I-10-4(24) REINF. STEEL STRUCT STEEL FOR UNIT SIZE
STRUCTURE NAME
NB/EB
DATE BY
SB/WB
ITEM DESCRIPTION Main Girders Cover PL@Pier #1 Cover PL@Pier #1 Cover PL@Pier #2 Cover PL@Pier #2 Splices
W36x135 PL 3/8x11 Ends PL 5/8x11 Ends PL �x11�
UNIT WEIGHT (PER FT) 135 14.00 9.56 23.40 15.90 19.60
UNIT LENGTH (FT) 247.16 13.00 1.50 16.00 1.50 2.54
NO OF UNITS (PER ITEM) 5 2 2 2 2 2
NO OF ITEMS 1 10 20 5 10 20
TOTAL WEIGHT 166,833 3,640 574 3,744 477 1,992 REVISION
Bolts in Splices Welds for Cover PL Shear Connector Studs
7/8 f 5/16"Fillet
.924 .1 6 6
204
94 1
20 5
Subtotal
�"fx4" .615
1,737 169 183,622 415 415 481 147 2,391 10,441 1,004 1,086 1 ,155
Subtotal
Stiff PL Welds for above Diaphragms Diaphragms Bolts for above Stiff PL Stiff PL PL � x5 5/16"Fillet [18x42.7 [15x33.9 7/8"f PL �x5 PL 3/8x5 8.5 .1 6 6 42.7 33.9 1.101 12.80 6 .38 2.83 7 .7 8 7.0 7.00 2.80 2 .83 20 114 8 44 114 30 8 1 1 1 1 8 1 8
Exp Joint
3x3x3/8
7.20
28.00
2
2
806
Anchors for above Welds
5/8f � Fillet
1.33 .106
29.00 29.00
1 .167
2 4 Subtotal
Total
Round TOTAL TO NEAREST 5 LBS.
Use
77 2 885 201,629 201,630
Lbs. Lbs.
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Listed below are the items which are to be included or excluded in the total of structural steel:
Inclusion List for Structural Steel
1. Structural steel for use in bridge structures consists of rolled shapes, plate girders, shear connectors, plates, bars, angles and other items as defined in this inclusion list. Areas and weights of steel sections amy be found in the A.I.S.C. Manual of Steel Construction. As shown in the A.I.S.C. Manual, the weight of rolled beams is given in pounds per linear foot. In figuring weight for welded plate girders, it is necessary that each plate differing in width, thickness or length be listed separately. The weight of plates greater than 36 inches in width should be increased by a percentage of the basic weight according to Table7 below. This is to allow for the A.S.T.M. permissible overrun of plates. TABLE 7 STRUCTURAL STEEL PLATE WEIGHT INCREASE EXPRESSED IN PERCENTAGE OF NOMINAL WEIGHT Specified Thickness Inches 3/16 to � excl � to 5/16 " 5/16 to 3/8 " 3/8 to 7/16 " 7/16 to � " � to 5/8 " 5/8 to � " � to 1 " 1 to 2 Incl. Over 36 to 48 Incl 3 2.5 2.3 2 2 2 1.8 1.8 Over 48 to 60 excl 4 3.5 3 2.5 2.3 2 2 2 1.8 60 to 72 to 70 84 excl 4.5 4 3.5 3 2.5 2.3 2 2 2 excl 5 4.5 4 3.5 3 2.5 2.3 2 2 84 to 96 excl 6 5 4.5 4 3.5 3 2.5 2.3 2 96 to 108 excle 7 6 5 4.5 4 3.5 3 2.5 2.3 108 to 120 excl 8 7 6 5 4.5 4 3.5 3 2.5 120 to 132 excl 9 8 7 6 5 4.5 4 3.5 3 132 to 144 excl 9.5 8 7.5 6.5 5.5 4.5 4 3.5 144 to 168 excl 168 and over
9.5 8 7 6 5 4.5 4
9 8 6 6 5.5 4.5
TABLE 8 WEIGHT OF STUD SHEAR CONNECTORS Stud Diameter � 5/8 � 7/8 Weight in pounds per 100 studs having in-place length of 3 in. 4 in. 5 in. 6 in. 7 in. 21.0 27.0 33.0 45.0 39.0 33.6 43.2 52.8 72.0 62.4 49.0 61.5 74.0 99.0 86.5 64.0 81.0 98.0 132.0 115.0
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2. BOLTS - All fasteners shall be high-strength bolts, AASHTO M164 (ASTM A325) or AASHTO M253(ASTM A490). Weights of components, including washers, may be found in the A.I.S.C. Manual of Steel Construction. Add 3% if galvanized. 3. WELDS - The weight of fillet welds shall be included in the weight of structural steel. In Table 9 below, a weight per linear foot is given for different sizes of fillet welds. For butt welds, plug welds, etc. no addition or deduction is made for weight calculations. TABLE 9 WEIGHT IN LBS OF WELDS PER LINEAR FOOT 45 degree fillet weld SIZE WEIGHT SIZE WEIGHT 1/8 .027 5/8 .664 3/ 1 6 .060 11/16 .804 1/ 4 .106 3/4 .956 5/16 .166 13/16 1.12 3/8 .239 7/8 1.30 7/ 1 6 .326 15/16 1.50 1/ 2 .425 1" 1.70 9/16 .538
4. The weight of deck drains should be included in the weight of structural steel for the deck.
Exclusion List for Structural Steel
1. 2. 3. 4. 5. 6. 7. Erection bolts. Pedestrian rail and accessories. Bumper (nose) angles for approach slabs. Steel "H" piling or steel encased in concrete piles. Fabricated steel supports or strengthened sections for erection. Deck joint assemblies. Abutment and pier steel bearings.
Structural Steel (Miscellaneous)
All other structural steel items including rockers, rollers, bearing plates, pins and nuts, plates, shapes for bridge sign supports, corresponding weld metal, nuts and bolts, and similar steel items not covered in other contract items will be measured for payment as structural steel (miscellaneous). Quantities should be separated by grade for structural steel. For steel bridges, A36 steel should be listed under Item No. 6040001 while other grades should be listed under Item No. 6040002 with the appropriate grade filled in with the parenthesis. Structural steel weights are not figured for concrete structures. A list of Bid Item Numbers, Items and units for various structural steel follows:
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ITEM NO. 6040001 6040002 6040003
IT E M STRUCTURAL STEEL STRUCTURAL STEEL ( ) STRUCTURAL STEEL (MISC)
UNIT LB LB LB
Structural Excavation
Each amount of structural excavation as shown in the approximate quantities table for items such as abutments and piers is to be rounded to the nearest 5 cu. Yds. Structural excavation limits for piers are bounded on the sides by vertical planes 1'-6" outside the limits of the footing, by the ground line on the top and the bottom of the footing on the bottom. When neat line excavation is called for on the plans or by the standard, the volume not excavated shall be deducted from the above. Structural excavation for abutments is figured with the same limits as described for pier excavation. In many instances abutments are built on approach fills. The depth of structural excavation into the approach fill is figured from the berm elevation to the bottom of the abutment cap beam and no neat line excavation is figured. For pier footings and abutment cap beams on piles, do not use neat line excavation. Excavation for abutment wings has the same 1'-6" limit as the main cap beam and neat line excavation where applicable. Figure 10, Structural Excavation Payment Limits, is shown for typical conditions. Actual payment limits for each structure shall be included with the structure drawings. A list of Bid Item Numbers, Items and Units for structural excavation follows: ITEM NO. 2030501 IT E M STRUCTURAL EXCAVATION UNIT CY
Structure Backfill
Each amount of structure backfill as shown in the approximate quantities table for items such as abutments and piers is to be rounded to the nearest 5 cubic yards. Structure backfill for abutments is figured as follows: When an abutment falls below the existing ground level, structure backfill is figured within structural excavation limits on the approach slab side of the abutment only. When an abutment is built above the existing ground level, an additional area under the
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approach slab is added. Measuring is to be parallel to the centerline of the roadway. The abutment wings enclose this area. Structure backfill is required for piers only when the pier falls within the roadway prism. When the roadway is on one side of a pier only, structure backfill is figured only on the side of the pier. Figure 11, Structure Backfill Payment Limits, is shown for typical conditions. Actual payment limits for each structure shall be included with the structure drawings. A list of Bid Item Numbers, Items and Units for structure backfill follows: ITEM NO. 2030506 IT E M STRUCTURE BACKFILL UNIT CY
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FIGURE 10
STRUCTURAL EXCAVATION PAYMENT LIMITS.
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FIGURE 11 STRUCTURE BACKFILL PAYMENT LIMITS.
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Drilled Shafts
Drilled shafts are bid by the linear foot. The item for drilled shafts includes the drilling, any casing, the concrete and all reinforcing steel embedded in the shaft. Quantities are rounded to the nearest foot for each sub item such as abutments and piers. Quantities are figured separately for each size and separated into two categories: drilled shafts drilled into rock and drilled shafts drilled into soil. Standard sizes are listed below. For special size shafts use Item Number 6090148 and fill in the specified diameter in inches within the parenthesis. For shafts in rock use Item Number 6091030 and fill in the specified diameter in inches within the parenthesis. A list of Bid Item Numbers, Items and Units for drilled shafts follows: ITEM NO. 6090018 6090024 6090030 6090036 6090042 6090048 6090054 6090060 6090066 6090072 6090078 6090084 6090096 6090148 6091030 IT E M DRILLED SHAFT FOUNDATION (18") DRILLED SHAFT FOUNDATION (24") DRILLED SHAFT FOUNDATION (30") DRILLED SHAFT FOUNDATION (36") DRILLED SHAFT FOUNDATION (42") DRILLED SHAFT FOUNDATION (48") DRILLED SHAFT FOUNDATION (54") DRILLED SHAFT FOUNDATION (60") DRILLED SHAFT FOUNDATION (66") DRILLED SHAFT FOUNDATION (72") DRILLED SHAFT FOUNDATION (78") DRILLED SHAFT FOUNDATION (84") DRILLED SHAFT FOUNDATION (96") DRILLED SHAFT FOUNDATION ( ) DRILLED SHAFTS (ROCK) ( ) UNIT LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF
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Driven Piles
Driven piles consist of H-piles, pipe piles and precast piles. Payment is divided into furnishing the pile, driving the pile and splicing, when required. There is no direct estimate for splicing. When an H-pile is specified other than the four sizes shown, items 6030012 and 6030194 should be used and the size placed in the parenthesis. When driven piles other than H-piles are specified, items 6030194 should be used and the type of pile used placed in the parenthesis. When piles must be driven deeper than specified on the plans to develop their strength, the contractor is paid to splice a new section onto the portion of the pile already driven. The cost equals five times the bid price for furnishing the piles. For quantity and payment purposes, two feet is added to the estimated length of a pile. Refer to Figure 12 for a diagram. A list of Bid Item Numbers, Items and Units for driven piles follows: ITEM NO. 6030003 6030005 6030008 6030010 6030012 6030013 6030190 6030191 6030192 6030193 6030194 6030195 6030303 6030305 6030308 6030310 6030312 6030313 ITEM FURNISHING PILES (STEEL) (HP12x53) FURNISHING PILES (STEEL) (HP12x74) FURNISHING PILES (STEEL) (HP14x89) FURNISHING PILES (STEEL) (HP14x117) FURNISH HP PILES FURNISH PILES ( ) DRIVE HP 12 x 53 PILES DRIVE UP 12 x 74 PILES DRIVE HP 14 x 89 PILES DRIVE HP 14 x 117 PILES DRIVE HP PILES ( ) DRIVE PILES ( ) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030003) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030005) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030008) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030010) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030012) SPLICING PILE (5 TIMES UNIT PRICE OF 6030013) UNIT LF LF LF LF LF LF LF LF LF LF LF LF EA EA EA EA EA EA
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FIGURE 12 LENGTH OF PILING
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Precast Prestressed Concrete Members
Precast prestressed concrete members consist of AASHTO standard or modified I-girders, box beams and voided slabs. The bid items are calculated by the linear foot. The total sum of the lengths of all girders are rounded to the nearest foot. The bid item includes reinforcing, concrete, prestressing strand, anything else embedded in the girder and also includes transportation and erection in place. A list of Bid Item Numbers, Items and Units for these members follows: ITEM NO. 6014950 6014951 6014952 6014953 6014954 6014955 6014956 6014957 6014958 6014959 6014960 6014961 6014962 6014963 6014964 6014965 6014966 6014967 6014968 6014969 6014970 6014971 6014972 6014973 ITEM PRECAST, P/S MEMBER (AASHTO TYPE 2 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 3 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 4 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 5 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 6 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 5 MOD. GR.) PRECAST, P/S MEMBER (AASHTO TYPE 6 MOD. GR.) PRECAST, P/S MEMBER (BOX BEAM TYPE BI-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BII-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BIII-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BIV-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BI-48) PRECAST, P/S MEMBER (BOX BEAM TYPE BII-48) PRECAST, P/S MEMBER (BOX BEAM TYPE BII-48) PRECAST, P/S MEMBER (BOX BEAM TYPE BIV-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SI-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SII-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SII-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SIV-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SI-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SII-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SIII-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SIV-48) PRECAST, P/S MEMBER ( ) UNIT LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF
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Miscellaneous Items
A list of miscellaneous Bid Item Numbers, Items and Units follows: ITEM NO. 2020002 2020008 2020009 6010501 6010801 6010831 6011130 6011131 6011132 6011133 6011134 6011371 6011372 6011373 6015101 6015102 6015200 6020001 6041001 6050101 6050201 6060040 6060041 6060042 6060043 6060044 6060045 6060046 6060047 6060048 6060075 6060076 IT E M REMOVE BRIDGE REMOVAL OF STRUCTURAL CONCRETE REMOVAL OF STRUCTURAL CONCRETE BRIDGE REPAIR BRIDGE DECK DRAIN ASSEMBLY GROOVE BRIDGE DECK 32 IN. F-SHAPE BRIDGE CONCRETE BARRIER AND TRANSITION (SD 1.01) 42 IN. F-SHAPE BRIDGE CONCRETE BARRIER AND TRANSITION (SD 1.02) COMBINATION PEDESTRIAN-TRAFFIC BRIDGE RAILING (SD 1.04) PEDESTRIAN FENCE FOR BRIDGE RAILING SD 1.04 (SD 1.05) TWO TUBE BRIDGE RAIL (SD 1.06) APPROACH SLAB (SD 2.01) ANCHOR SLAB-TYPE 1 (SD 2.02) ANCHOR SLAB-TYPE 2 (SD 2.03) RESTRAINERS, VERTICAL EARTHQUAKE (FIXED) RESTRAINERS, VERTICAL EARTHQUAKE(EXPANSION) HIGH-LOAD MULTI-ROTATIONAL BEARINGS PRESTRESSING CAST-IN-PLACE CONCRETE JACKING BRIDGE SUPERSTRUCTURE PLACE DOWELS LOAD TRANSFER DOWELS BRIDGE SIGN STRUCTURE (TUBULAR) (40' TO 70') BRIDGE SIGN STRUCTURE (TUBULAR) (70' TO 94') BRIDGE SIGN STRUCTURE (TUBULAR) (94' TO 106') BRIDGE SIGN STRUCTURE (TUBULAR) (106' TO 130') BRIDGE SIGN STRUCTURE (TUBULAR) (130' TO 142') TUBULAR FRAME SIGN STRUCTURE (TYPE 1F) (SD 9.20) TUBULAR FRAME SIGN STRUCTURE (TYPE 2F) (SD 9.20) TUBULAR FRAME SIGN STRUCTURE (TYPE 3F) (SD 9.20) TUBULAR FRAME SIGN STRUCTURE (TYPE 4F) (SD 9.20) FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 1F) (SD 9.20) FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 2F) (SD 9.20) UNIT LUMP SUM LUMP SUM CY LUMP SUM LS SQ YD LF LF LF LF LF SF SF SF EA EA EA LS LUMP SUM EA EA EA EA EA EA EA EA EA EA EA EA EA
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6060078 6060079 6060131 6060132 6060133 6060134 6060161 6060162 6060247 6060254 6060255 6060256 6060257 6100001 6100011 7320471 7379111 9050430 9100008 9120001 9140136 9140137 9210001
FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 3F) (SD 9.20) FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 4F) (SD 9.20) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 1C) (SD 9.10) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 2C) (SD 9.10) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 3C) (SD 9.10) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 4C) (SD 9.10) SIGN STRUCTURE (MEDIAN, TWO SIDED) (SD 9.01) SIGN STRUCTURE (MEDIAN, ONE SIDED) (SD 9.02) FOUNDATION FOR SIGN STRUCTURE (MEDIAN) (SD 9.01 OR SD 9.02) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 1C) (SD 9.10) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 2C) (SD 9.10) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 3C) (SD 9.10) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 4C) (SD 9.10) PAINTING STRUCTURAL STEEL PAINT BRIDGE BRIDGE JUNCTION BOX VARIABLE MESSAGE SIGN ASSEMBLY INSTALLATION THRIE BEAM GUARD RAIL TRANSITION SYSTEM (SD 1.03) CONCRETE BARRIER (TEMPORARY BRIDGE) SHOTCRETE SOUND BARRIER WALL (CONCRETE) (SD 8.01) SOUND BARRIER WALL (MASONARY) (SD 8.02) SLOPE PAVING (STD. B-19.20 AND B-19.21)
EA EA EA EA EA EA EA EA EA EA EA EA EA LUMP SUM LUMP SUM EA EA EA LF SQ YD SF SF SQ YD
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Arizona Department of Transportation Bridge Group
SECTION 2 - GENERAL DESIGN & LOCATION FEATURES
Chapter SCOPE DEFINITIONS LOCATION FEATURES Route Location Bridge Site Arrangement Clearances Environment Page Issue Date 2 2 4 4 5 6 9 9 9 9 10 10 10 14 15 16 17 17 17 18 19 23 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99
FOUNDATION INVESTIGATION
General Topographic Studies Safety Serviceability Constructibility Economy Bridge Aesthetics
DESIGN OBJECTIVES
HYDROLOGY AND HYDRAULICS
General Site Data Hydrologic Analysis Hydraulic Analysis Deck Drainage
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SCOPE
This section is intended to provide the Designer with sufficient information to determine the configuration and overall dimensions of a bridge. In recognition that many bridge failures have been caused by scour, hydrology and hydraulics are covered in detail. For a complete discussion of the information presented here, refer to the AASHTO LRFD Bridge Design Specifications, Section 2.
DEFINITIONS
Aggradation : A general and progressive buildup or raising of the longitudinal profile of the channel bed as a result of sediment deposition. Bridge Designer : The design team who produced the structural drawings and supporting documents for the bridge. Clear Zone : An unobstructed, relatively flat area beyond the edge of the traveled way for the recovery of errant vehicles. The traveled way does not include shoulders or auxiliary lanes. Clearance : An unobstructed horizontal or vertical space. Degradation: A general and progressive lowering of the longitudinal profile of the channel bed as a result of long-term erosion. Design Discharge: Maximum flow of water a bridge is expected to accommodate without exceeding the adopted design constraints. Design Flood for Bridge Scour: The flood flow equal to or less than the 100-year flood that creates the deepest scour at bridge foundations. The highway or bridge may be inundated at the stage of the design flood for bridge scour. The worst-case scour condition may occur for the overtopping flood as a result of the potential for pressure flow. Detention Basin: A stormwater management facility that impounds runoff and temporarily discharges it through a hydraulic outlet structure to a downstream conveyance system. Drip Groove: Linear depression in the bottom of components to cause water flowing on the surface to drop.
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Five-Hundred-Year Flood: The flood due to storm and/or tide having a 0.2 percent chance of being equaled or exceeded in any given year. Commonly referred to as the Superflood, used to check the structural adequacy of bridge foundations for that extreme design event. General or Contraction Scour: Scour in a channel or on a floodplain that is not localized at a pier or other obstruction to flow. In a channel, general/contraction scour usually affects all or most of the channel width and is typically caused by a contraction of the flow. Hydraulics : The science that deals with practical applications (as the transmission of energy or the effects of flow) of water or other liquid in motion. Hydrology: The science concerned with the occurrence, distribution, and circulation of water on the earth, including precipitation, runoff, and groundwater. In highway design, the process by which design discharges are determined. Local Scour: Scour in a channel or on a floodplain that is localized at a pier, abutment, or other obstruction to flow. One-Hundred-Year Flood: The flood due to storm and/or tide having a 1 percent chance of being equaled or exceeded in any given year. Overtopping Flood: The flood flow that, if exceeded, results in flow over a highway or bridge, over a watershed divide, or through structures provided for emergency relief. The worst-case scour condition may be caused by the overtopping flood. Stable Channel: A condition that exists when a stream has a bed slope and crosssection that allows its channel to transport the water and sediment delivered from the upstream watershed without significant degradation, aggradation, or bank erosion. Stream Geomorphology: The study of a stream and its floodplain with regard to its land forms, the general configuration of its surface, and the changes that take place due to erosion and the buildup of erosional debris. Superelevation: A tilting of the roadway surface to partially counterbalance the centrifugal forces on vehicles on horizontal curves. Superflood : Any flood or tidal flow with a flow rate greater than that of the 100-year flood but not greater than a 500-year flood. Estimated magnitude equals 1.7 times the 100-year flood. Watershed : An area confined by drainage divides, and often having only one outlet for discharge; the total drainage area contributing runoff to a single point. Waterway: Any stream, river, pond, lake, or ocean.
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Waterway Opening: Width or area of bridge opening at a specified stage, and measured normal to principal direction of flow.
LOCATION FEATURES Route Location
GENERAL The choice of location of bridges shall be supported by analyses of alternatives with consideration given to economic, engineering, social, and environmental concerns as well as costs of maintenance and inspection associated with the structures and with the relative importance of the above-noted concerns. Attention, commensurate with the risk involved, shall be directed toward providing for favorable bridge locations that: � � � � Fit the conditions created by the obstacle being crossed; Facilitate practical cost effective design, construction, operation, inspection and maintenance; Provide for the desired level of traffic service and safety; and Minimize adverse highway impacts.
WATERWAY AND FLOODPLAIN CROSSINGS Waterway crossings shall be located with regard to initial capital costs of construction and the optimization of total costs, including river channel training works and the maintenance measures necessary to reduce erosion. Studies of alternative crossing locations should include assessments of: � � � � The hydrologic and hydraulic characteristics of the waterway and its floodplain, including channel stability and flood history. The effect of the proposed bridge on flood flow patterns and the resulting scour potential at bridge foundations; The potential for creating new or augmenting existing flood hazards; and Environmental impacts on the waterway and its floodplain.
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Bridges and their approaches on floodplains should be located and designed with regard to the goals and objectives of floodplain management, including; � � � � � � Prevention of uneconomic, hazardous, or incompatible use and development of floodplains; Avoidance of significant transverse and longitudinal encroachments, where practicable; Minimization of adverse highway impacts and mitigation of unavoidable impacts, where practicable; Consistency with the intent of the standards and criteria of the National Flood Insurance Program, where applicable; Long-term aggradation or degradation; and Commitments made to obtain environmental approvals
It is generally safer and more cost effective to avoid hydraulic problems through the selection of favorable crossing locations than to attempt to minimize the problems at a later time in the project development process through design measures. Experience at existing bridges should be part of the calibration or verification of hydraulic models, if possible. Evaluation of the performance of existing bridges during past floods is often helpful in selecting the type, size, and location of new bridges.
Bridge Site Arrangement
GENERAL The location and the alignment of the bridge should be selected to satisfy both on-bridge and under-bridge traffic requirements. Consideration should be given to possible future variations in alignment or width of the waterway, highway, or railway spanned by the bridge. Where appropriate, consideration should be given to future addition of mass-transit facilities or bridge widening. TRAFFIC SAFETY Protection of structures Consideration shall be given to safe passage of vehicles on or under a bridge. The hazard to errant vehicles within the clear zone should be minimized by locating obstacles at a safe distance from the travel lanes.
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Pier columns or walls for grade separation structures should be located in conformance with the clear zone concept as contained in Chapter 3 of the AASHTO Roadside Design Guide. Where the practical limits of structure costs, type of structure, volume and design speed of through traffic, span arrangement, skew, and terrain make conformance with the Roadside Design Guide impractical, the pier or wall should be protected by the use of guardrail or other barrier devices. The guardrail or other device should, if practical, be independently supported, with its roadway face at least 2.0 FT from the face of pier or abutment, unless a rigid barrier is provided. The intent of providing structurally independent barriers is to prevent transmission of force effects from the barrier to the structure to be protected. The face of the guardrail or other device should be at least 2.0 FT outside the normal shoulder line. Protection of Users Railings shall be provided along the edges of structures conforming to the requirements of Section 13 of AASHTO LRFD Bridge Design Specifications. All protective structures shall have adequate surface features and transitions to safely redirect errant traffic. Geometric Standards Requirements of the AASHTO publication A Policy on Geometric Design of Highways and Streets shall either be satisfied or exceptions thereto shall be justified and documented. Width of travel lanes and shoulders shall meet the requirements established by the roadway engineer. Road Surfaces Road surfaces on a bridge shall be given antiskid characteristics, crown, drainage, and superelevation in accordance with A Policy on Geometric Design of Highways and Streets.
Clearances
NAVIGATIONAL Permits for construction of a bridge over navigable waterways shall be obtained from the U.S. Coast Guard and/or other agencies having jurisdiction. Navigational clearances, both vertical and horizontal, shall be established in cooperation with the U.S. Coast Guard. The Colorado River is the only navigable waterway in Arizona with U.S. Coast Guard jurisdiction. Certain reservoirs have bridges over navigable waterway passage with other agencies having jurisdiction.
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VERTICAL CLEARANCE AT STRUCTURES The following are minimum vertical clearance standards for highway traffic structures, pedestrian overpasses, railroad overpasses, tunnels and sign structures. Lesser clearances may be used only under very restrictive conditions, upon individual analysis and with the approval of the Assistant State Engineer-Roadway Group. HIGHWAY TRAFFIC STRUCTURES The design vertical clearance to structures passing over all roadways shall be at least 16'-6 over the entire roadway width, including auxiliary lanes and shoulders. An allowance of 6 inches is included to accommodate future resurfacing. This allowance may be waived if the roadway under the structure is surfaced with portland cement concrete. Consideration should be given to providing 16'-6 clearance at interchange structures having large volumes of truck traffic and at other structures over highways carrying very high traffic volumes, regardless of the highway system classification. PEDESTRIAN OVERPASSES Because of their lesser resistance to impacts, the minimum design vertical clearance to pedestrian overpasses shall be 17'-6 regardless of the highway system classification. An allowance of 6 inches is included to accommodate future resurfacing. TUNNELS The minimum design vertical clearance for tunnels shall be at least 16'-6 for freeways, arterials and all other State Highways and at least 15'-6 for all other highways and streets. SIGN STRUCTURES Because of their lesser resistance to impacts, the minimum design vertical clearance to sign structures shall be 18'-0 regardless of the highway system classification. An allowance of 6 inches is included to accommodate future resurfacing. HORIZONTAL CLEARANCE AT STRUCTURES The bridge width shall not be less than that of the approach roadway section, including shoulders or curbs, gutters, and sidewalks.
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No object on or under a bridge, other than a barrier, should be located closer than 4.0 FT to the edge of a designated traffic lane. The inside face of a barrier should not be closer than 2.0 FT to either the face of the object or the edge of a designated traffic lane. RAILROAD OVERPASS Structures designed to pass over a railroad shall be in accordance with standards established and used by the affected railroad in its normal practice. These overpass structures shall comply with applicable federal, state, county, and municipal laws. Structures over railways shall provide a minimum clearance of 23 feet above top of rail, except that overhead clearance greater than 23 feet may be approved when justified on the basis of railroad electrification. No additional allowance shall be provided for future track adjustments. Regulations, codes, and standards should, as a minimum, meet the specifications and design standards of the American Railway Engineering Association, the Association of American Railroads, and AASHTO. Requirements of the individual railroads in Arizona are contained in regulations published by the Arizona Corporation Commission. Attention is particularly called to the following chapters in the Manual for Railway Engineering (AREA 1991): � � � � � Chapter 7 � Timber Structures, Chapter 8 � Concrete Structures and Foundations, Chapter 9 � Highway-Railroad Crossings, Chapter 15 � Steel Structures, and Chapter 18 � Clearances.
The provisions of the individual railroads and the AREA Manual should be used to determine: � � � � � Clearances, Loadings, Pier protection, Waterproofing, and Blast protection.
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Environment
The impact of a bridge and its approaches on local communities, historic sites, wetlands, and other aesthetically, environmentally, and ecologically sensitive areas shall be considered. Compliance with state water laws; federal and state regulations concerning encroachment on floodplains, fish, and wildlife habitats; and the provisions of the National Flood Insurance Program shall be assured. Stream geomorphology, consequences of riverbed sour, and removal of embankment stabilizing vegetation, shall be considered. Stream, i.e., fluvial, geomorphology is a study of the structure and formation of the earth's features that result from the forces of water. For purposes of this section, this involves evaluating the stream's potential for aggradation, degradation, or lateral migration.
FOUNDATION INVESTIGATION General
A subsurface investigation, including borings and soil tests, shall be conducted in accordance with the provisions of AASHTO to provide pertinent and sufficient information for the design of substructure units. The type and cost of foundations should be considered in the economic and aesthetic studies for location and bridge alternate selection. For bridge replacement or rehabilitation, existing geotechnical data may provide valuable information for initial studies.
Topographic Studies
Current topography of the bridge site shall be established via contour maps and photographs. Such studies shall include the history of the site in terms of movement of earth masses, soil and rock erosion, and meandering of waterways.
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DESIGN OBJECTIVES Safety
The primary responsibility of the Bridge Designer shall be providing for the safety of the public.
Serviceability
DURABILITY Materials The contract documents shall call for quality materials and for the application of high standards of fabrication and erection. Structural steel shall be self-protecting, or have long-life coating systems. Reinforcing bars and prestressing strands in concrete components, which may be expected to be exposed to airborne or waterborne salts, shall be protected by an appropriate combination of epoxy and/or composition of concrete, including airentrainment and a nonporous painting of the concrete surface. Prestress strands in cable ducts shall be grouted or otherwise protected against corrosion. Attachments and fasteners used in wood construction shall be of stainless steel, malleable iron, aluminum, or steel that is galvanized, cadmium-plated, or otherwise coated. Wood components shall be treated with preservatives. Aluminum products shall be electrically insulated from steel and concrete components. Protection shall be provided to materials susceptible to damage from solar radiation and/or air pollution. Consideration shall be given to the durability of materials in direct contact with soil, sun and/or water. Self-Protecting Measures Continuous drip grooves shall be provided along the underside of a concrete deck at a distance not exceeding 10.0 IN from the fascia edges. Where the deck is interrupted by a sealed deck joint, all top surfaces of piers and abutments, other than bearing seats, shall have a minimum slope of 5 percent toward their edges. For open deck joints, this minimum slope shall be increased to 15 percent. In the case of open deck joints, the bearings shall be protected against contact with salt and debris.
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Wearing surfaces shall be interrupted at the deck joints and shall be provided with a smooth transition to the deck joint device. INSPECTABILITY Inspection ladders, walkways, catwalks, covered access holes, and provision for lighting, if necessary, shall be provided where other means of inspection are not practical. Where practical, access to allow manual or visual inspection, including adequate headroom in box sections, shall be provided to the inside of cellular components and to interface areas, where relative movement may occur. MAINTAINABILITY Structural systems whose maintenance is expected to be difficult should be avoided. Where the climatic and/or traffic environment is such that the bridge deck may need to be replaced before the required service life, either provisions shall be shown on the contract plans for the replacement of the deck or additional structural resistance shall be provided. Areas around bearing seats and under deck joints should be designed to facilitate jacking, cleaning, repair, and replacement of bearings and joints. Jacking points shall be indicated on the plans, and the structure shall be designed for the jacking forces. Inaccessible cavities and corners should be avoided. Cavities that may invite human or animal inhabitants shall either be avoided or made secure. RIDEABILITY The deck of the bridge shall be designed to allow for the smooth movement of traffic. On paved roads, a structural transition slab should be located between the approach roadway and the abutment of the bridge. Construction tolerances, with regard to the profile of the finished deck, shall be indicated on the plans or in the specifications or special provisions. The number of deck joints shall be kept to a practical minimum. Edges of joints in concrete decks exposed to traffic should be protected from abrasion and spalling. The plans for prefabricated joints shall specify that the joint assembly be erected as a unit, if feasible. Where concrete decks without an initial overlay are used, an additional thickness of 0.5IN to permit correction of the deck profile by grinding, and to compensate for thickness loss due to abrasion will be provided.
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UTILITIES IN STRUCTURES Where utility conflicts exist; water, power, telephone, cable TV and gas lines will be relocated as required for construction of the project. Where it is feasible and reasonable to locate utility lines elsewhere, attachment to structures will not be permitted. Trenching in the vicinity of existing piers or abutments shall be kept a sufficient distance from footings to prevent undercutting of existing footings or to prevent disturbing foundation soils for future foundations. Where other locations prove to be extremely difficult and very costly, utility lines, except natural gas, may be allowed in the structures. Natural gas encroachments will be evaluated under the following policy: A. Cases were gas line attachments to structures will not be considered under any condition: 1. Grade separation structures carrying vehicular traffic on or over freeways. 2. Inside closed cell-type box girder bridges. 3. High pressure transmission lines over 60 psi and/or distribution lines of over 6 inches in diameter. 4. Gas lines over minor waterway crossings where burial is feasible B. Gas line attachments on structures will be considered under the following cases or conditions: 1. Each case will be judged on its own merit with the utilities providing complete justification as to why alternative locations are not feasible. 2. Economics will not be a significant factor considered in the feasibility issue. 3. Open girder type structures across major rivers. 4. Pedestrian or utility bridges where proper vented casings and other safety systems are used. 5. All lines are protected by casements. Provisions for accommodation of relocated and future utilities on structures shall be coordinated through the Utility and Railroad Engineering Section for ADOT projects, or as appropriate, through Statewide Project Management Section and/or a consultant for other projects.
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General Policy Support bracket details and attachments for all utilities will require Bridge Group approval. All approved utilities shall have individual sleeved casings, conduits or ducts as appropriate. All utilities carrying liquids shall be placed inside casing through the entire length of the structure. The casing shall be designed to carry full service pressure so as to provide a satisfactory containment in case the utility is damaged or leaks. Water lines, telephone conduits, power lines, cable TV lines, supports or other related items will not be permitted to be suspended below or attached to the exterior of any new or existing structure. Product lines for transmitting volatile fluids will not be permitted to be attached to or suspended from or placed within any new or existing structure. Manholes or access openings for utilities will not be permitted in bridge decks, webs, bottom slabs or abutment diaphragms. On special major projects, ADOT design costs will be assessed to the company Utility Company Responsibility The utility company is responsible for obtaining necessary information regarding the proposed construction schedule for the project. The company shall submit a request including justification for attaching to the structure and preliminary relocation plans including line weights and support spacing as early as possible but no later than the completion of preliminary structural plans. The company shall submit complete plans and specifications of their proposed installation at least 20 working days prior to the schedule C & S Date. The utility company shall be responsible for the design of all conduits, pipes, sleeves, casings, expansion devices, supports and other related items including the following information: 1. Number and size of conduits for power, telephone and cable TV lines. 2. Size and schedule of carrier pipe for water lines. 3. Size and schedule of sleeved casings. 4. Spacing and details of support brackets.
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5. Expansion device details. 6. Total combined weight of carrier pipe and transmitted fluids, conduits, casings, support brackets, expansion joints and other related items. 7. Design calculations. 8. Submit permit request through the District. Bridge Designer Responsibility The Bridge Designer shall be responsible for the following aspects of the design : 1. Determination of how many lines, if any, the structure can accommodate. 2. Determination of where such lines should be located within a structure. 3. Determination of the size of the access openings and design of the required reinforcing. 4. Identification of installation obstacles related to required sequencing of project. 5. Tracking man-hours associated with utility relocations for cost recovery, when appropriate. Usually utilities will be accommodated by providing individual access openings for casings and sleeves to pass through. Access openings should be 2 inches larger than the diameter of the casings or sleeves and spaced as required by structural considerations. For box girder bridges, access openings should be located as low as possible but no lower than 10 inches above the top of the bottom slab to allow for support brackets to be supported from the bottom slab. Where possible all utilities shall be supported from the bottom slab for box girder bridges. For precast or steel girder bridges, the utilities shall not be placed in the exterior girder bay and they shall be supported from the deck slab, rather than from the diaphragms.
Constructibility
Bridges should be designed in a manner such that fabrication and erection can be performed without undue difficulty or distress and that locked-in construction force effects are within tolerable limits.
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When the method of construction of a bridge is not self-evident or could induce unacceptable locked-in stresses, at least one feasible method shall be indicated in the contract documents. If the design requires some strengthening and/or temporary bracing or support during erection by the selected method, indication of the need thereof shall be indicated in the contract documents. Details that require welding in restricted areas or placement of concrete through congested reinforcing should be avoided. Climatic and hydraulic conditions that may affect the construction of the bridge shall be considered.
Economy
GENERAL Structural types, span lengths, and materials shall be selected with due consideration of projected cost. The cost of future expenditures during the projected service life of the bridge should be considered. Regional factors, such as availability of material, fabrication, location, shipping, and erection constraints, shall be considered. If data for the trends in labor and material cost fluctuation is available, the effect of such trends should be projected to the time the bridge will likely be constructed. Cost comparisons of structural alternatives should be based on long-range considerations, including inspection, maintenance, repair, and/or replacement. Lowest first cost does not necessarily lead to lowest total cost. ALTERNATIVE PLANS In instances where economic studies do not indicate a clear choice, the State Bridge Engineer may require that alternative contract plans be prepared and bid competitively. Designs for alternative plans shall be of equal safety, serviceability, and aesthetic value. Movable bridges over navigable waterways should be avoided to the extent feasible. Where movable bridges are proposed, at least one fixed bridge alternative should be included in the economic comparisons.
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Bridge Aesthetics
Bridges should complement their surroundings, be graceful in form, and present an appearance of adequate strength. Significant improvements in appearance can often be made with small changes in shape or position of structural members at negligible cost. For prominent bridges, however, additional cost to achieve improved appearance is often justified, considering that the bridge will likely be a feature of the landscape for 75 or more years. Engineers should seek more pleasant appearance by improving the shapes and relationships of the structural component themselves. The application of extraordinary and nonstructural embellishment should be avoided. The following guidelines should be considered: � � � Alternative bridge designs without piers or with few piers should be studied during the site selection and location stage and refined during the preliminary design stage. Pier form should be consistent in shape and detail with the superstructure. Abrupt changes in the form of components and structural type should be avoided. Where the interface of different structural types cannot be avoided, a smooth transition in appearance from one type to another should be attained. Attention to details, such as deck drain downspouts, should not be overlooked. The use of the bridge as a support for message or directional signing or lighting should be avoided wherever possible. Transverse web stiffeners, other than those located at bearing points, should not be visible in elevation. For spanning deep ravines, arch-type structures should be preferred.
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The most admired modern structures are those that rely for their good appearance on the forms of the structural components themselves: � � � Components are shaped to respond to the structural function. They are thick where the stresses are greatest and thin where the stresses are smaller. The function of each part and how the function is performed is visible. Components are slender and widely spaced, preserving views through the structure.
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The bridge is seen as a single whole, with all members consistent and contributing to that whole; for example, all elements should come from the same family of shapes, such as shapes with rounded edges. The bridge fulfills its function with a minimum of material and minimum number of elements. The size of each member compared with the others is clearly related to the overall structural concept and the job the component does, and The bridge as a whole has a clear and logical relationship to its surroundings.
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HYDROLOGY AND HYDRAULICS General
Hydrologic and hydraulic studies and assessments of bridge sites for stream crossings shall be completed as part of the preliminary plan development. The detail of these studies should be commensurate with the importance of and risks associated with the structure. Temporary structures for the Contractor's use or for accommodating traffic during construction shall be designed with regard to the safety of the traveling public and the adjacent property owners, as well as minimization of impact on floodplain natural resources. ADOT may permit revised design requirements consistent with the intended service period for, and flood hazard posed by, the temporary structure. Contract documents for temporary structures shall delineate the respective responsibilities and risks to be assumed by ADOT and the Contractor. Evaluation of bridge design alternatives shall consider stream stability, backwater, flow distribution, stream velocities, scour potential, flood hazards, and consistency with established criteria for the National Flood Insurance Program.
Site Data
A site-specific data collection plan shall include consideration of: � � Collection of aerial and/or ground survey data for appropriate distances upstream and downstream from the bridge for the main stream channel and its floodplain; Estimation of roughness elements for the stream and the floodplain within the reach of the stream under study;
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Sampling of streambed material to a depth sufficient to ascertain material characteristics for scour analysis; Subsurface borings; Factors affecting water stages, including high water from streams, reservoirs, detention basins, and flood control structures and operating procedures; Existing studies and reports, including those conducted in accordance with the provisions of the National Flood Insurance Program or other flood control programs; Available historical information on the behavior of the stream and the performance of the structure during past floods, including observed scour, bank erosion, and structural damage due to debris or ice flows; and Possible geomorphic changes in channel flow.
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Hydrologic Analysis
The following flood flows should be investigated, as appropriate, in the hydrologic studies: � � � For assessing flood hazards and meeting floodplain management requirements � the 100-year flood; For assessing risks to highway users and damage to the bridge and its roadway approaches � the overtopping flood and/or the design flood for bridge scour; For assessing catastrophic flood damage at high risk sites � a check flood of a magnitude selected by the Bridge Designer as appropriate for the site conditions and the perceived risk; For investigating the adequacy of bridge foundations to resist scour � the check flood for bridge scour; To satisfy ADOT design policies and criteria � design floods for waterway opening and bridge scour for the various functional classes of highways, as described in the ADOT Roadway Design Guidelines; To calibrate water surface profiles and to evaluate the performance of existing structures � historical floods, and To evaluate environmental conditions � low or base flow information
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Hydraulic Analysis
GENERAL The Bridge Designer shall utilize analytical models and techniques that have been approved by ADOT and that are consistent with the required level of analysis as described in the ADOT Roadway Design Guidelines. STREAM STABILITY Studies shall be carried out to evaluate the stability of the waterway and to assess the impact of construction on the waterway. The following items shall be considered: � � Whether the steam reach is degrading, aggrading, or in equilibrium; For stream crossing near confluences, the effect of the main stream and the tributary on the flood stages, velocities, flow distribution, vertical and lateral movements of the stream, and the effect of the foregoing conditions on the hydraulic design of the bridge; Location of favorable stream crossing, taking into account whether the stream is straight, meandering, braided, or transitional, or control devices to protect the bridge from existing or anticipated future stream conditions; The effect of any proposed channel changes; The effect of aggregate mining or other operations in the channel; Potential changes in the rates or volumes of runoff due to land use changes; The effect of natural geomorphic stream pattern changes on the proposed structure; and The effect of geomorphic changes on existing structures in the vicinity of, and caused by, the proposed structure.
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For unstable streams or flow conditions, special studies shall be carried out to assess the probable future changes to the plan form and profile of the stream and to determine countermeasures to be incorporated in the design, or at a future time, for the safety of the bridge and approach roadways.
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BRIDGE WATERWAY The design process for sizing the bridge waterway shall include: � � The evaluation of flood flow patterns in the main channel and floodplain for existing conditions, and The evaluation of trial combinations of highway profiles, alignments, and bridge lengths for consistency with design objectives.
Where use is made of existing flood studies, their accuracy shall be determined. BRIDGE FOUNDATIONS General The structural, hydraulic, and geotechnical aspects of foundation design shall be coordinated and differences resolved prior to approval of preliminary plans. To reduce the vulnerability of the bridge to damage from scour and hydraulic loads, consideration should be given to the following general design concepts: � Set deck elevations as high as practical for the given site conditions to minimize inundation, or overtopping of roadway approach sections, and streamline the superstructure to minimize the area subject to hydraulic loads and the collection of ice, debris, and drifts. Utilize relief bridges, guide banks, dikes, and other river training devices to reduce the turbulence and hydraulic forces acting at the bridge abutments. Utilize continuous span designs. Anchor superstructures to their substructures where subject to the effects of hydraulic loads, buoyancy, ice, or debris impacts or accumulations. Provide for venting and draining of the superstructure. Where practical, limit the number of piers in the channel, streamline pier shapes, and align pier columns with the direction of flood flows. Avoid pier types that collect ice and debris. Locate piers beyond the immediate vicinity of stream banks. Locate abutments back from the channel banks where significant problems with ice/debris buildup, scour, or channel stability are anticipated, or where special environmental or regulatory needs must be met, e.g., spanning wetlands. Design piers within floodplains as river piers. Locate their foundations at the appropriate depth if there is a likelihood that the stream channel will shift during the life of the structure or that channel cutoffs are likely to occur.
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Where practical, use debris racks to stop debris before it reaches the bridge. Where significant debris buildup is unavoidable, its effects should be accounted for in determining scour depths and hydraulic loads. A majority of bridge failures in the United States and elsewhere are the result of scour. The added cost of making a bridge less vulnerable to damage from scour is small in comparison to the total cost of a bridge failure.
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Bridge Scour As required by Section 3, scour at bridge foundations is investigated for two conditions: � For the design flood for scour, the streambed material in the scour prism above the scour line shall be assumed to have been removed for design conditions. The design flood storm surge, tide, or mixed population flood shall be the more severe of the 100-year events or from an overtopping flood of lesser recurrence interval. For the check flood for scour, the stability of the bridge foundation shall be investigated for scour conditions resulting from a designated flood storm surge, tide, or mixed population flood not to exceed the 500-year event or from an overtopping flood of lesser recurrence interval. Excess reserve beyond that required for stability under this condition is not necessary. The extreme event limit state shall apply.
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If the site conditions, due to debris jams, and low tailwater conditions near stream confluences dictate the use of a more severe flood event for either the design or check flood for scour, the Bridge Designer may use such flood event. Spread footings on soil or erodible rock shall be located beyond the scour potential of the waterway. Spread footings on scour-resistant rock shall be designed and constructed to maintain the integrity of the supporting rock. Deep foundations with footings shall be designed to place the top of the footing below the estimated contraction scour depth where practical to minimize obstruction to flood flows and resulting local scour. Even lower elevations should be considered for pilesupported footings where the piles could be damaged by erosion and corrosion from exposure to stream currents. Where conditions dictate a need to construct the top of a footing to an elevation above the streambed, attention shall be given to the scour potential of the design. When fendering or other pier protection systems are used, their effect on pier scour and collection of debris shall be taken into consideration in the design. The design flood for scour shall be determined on the basis of the Bridge Designer's judgment of the hydrologic and hydraulic flow conditions at the site. The recommended procedure is to evaluate scour due to the specified flood flows and to design the foundation for the event expected to cause the deepest total scour.
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The recommended procedure for determining the total scour depth at bridge foundations is as follows: � � � � Estimate the long-term channel profile aggradation or degradation over the service life of the bridge; Estimate the effects of gravel mining on the channel profile, if appropriate; Estimate the long-term channel plan form changes over the service life of the bridge; As a design check, adjust the existing channel and floodplain cross-sections upstream and downstream of bridge as necessary to reflect anticipated changes in the channel profile and plan form; Determine the combination of existing or likely future conditions and flood events that might be expected to result in the deepest scour for design conditions.; Determine water surface profiles for a stream reach that extends both upstream and downstream of the bridge site for the various combinations of conditions and events under consideration; Determine the magnitude of contraction scour and local scour at piers and abutments; and Evaluate the results of the scour analysis, taking into account the variables in the methods used, the available information on the behavior of the watercourse, and the performance of existing structures during past floods. Also consider present and anticipate future flow patterns and the effect of the flow on the bridge. Modify the bridge design where necessary to satisfy concerns raised by the scour analysis and the evaluation of the channel plan form.
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Foundation designs should be based on the total scour depths estimated by the above procedure, taking into account appropriate geotechnical safety factors. Where necessary, bridge modifications may include: � � � � Relocation or redesign of piers or abutments to avoid areas of deep scour or overlapping scour holes from adjacent foundation elements, Addition of guide banks, dikes, or other river training works to provide for smoother flow transitions or to control lateral movement of the channel, Enlargement of the waterway area, or Relocation of the crossing to avoid an undesirable location.
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Foundations should be designed to withstand the conditions of scour for the design flood and the check flood. In general, this will result in deep foundations. The design of the foundations of existing bridges that are being rehabilitated should consider underpinning if scour indicates the need. Riprap and other scour countermeasures may be appropriate if underpinning is not cost effective. The stability of abutments in areas of turbulent flow shall be thoroughly investigated. Exposed embankment slopes should be protected with appropriate scour countermeasures. ROADWAY APPROACHES TO BRIDGE The design of the bridge shall be coordinated with the design of the roadway approaches to the bridge on the floodplain so that the entire flood flow pattern is developed and analyzed as a single, interrelated entity. Where roadway approaches on the floodplain obstruct overbank flow, the highway segment within the floodplain limits shall be designed to minimize flood hazards. Where diversion of flow to another watershed occurs as a result of backwater and obstruction of flood flows, an evaluation of the design shall be carried out to ensure compliance with legal requirements in regard to flood hazards in the watershed.
Deck Drainage
GENERAL The bridge deck and its highway approaches shall be designed to provide safe and efficient conveyance of surface runoff from the traveled way in a manner that minimizes damage to the bridge and maximizes the safety of passing vehicles. Transverse drainage of the deck, including roadway, bicycle paths, and pedestrian walkways, shall be achieved by providing a cross slope or superelevation sufficient for positive drainage. For wide bridges with more than three lanes in each direction, special design of bridge deck drainage and/or special rough road surfaces may be needed to reduce the potential for hydroplaning. Water flowing downgrade in the roadway gutter section shall be intercepted and not permitted to run into the bridge. Drains at bridge ends shall have sufficient capacity to carry all contributing runoff. In those unique environmentally sensitive instances where it is not possible to discharge into the underlying water course, consideration should be given to conveying the water in a longitudinal storm drain affixed to the underside of the bridge and discharging it into appropriate facilities on natural ground at bridge end. Where feasible, bridge decks should be watertight and all of the deck drainage should be carried to the ends of the bridge.
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A longitudinal gradient on bridges should be maintained. Zero gradients and sag vertical curves should be avoided. Design of the bridge deck and the approach roadway drainage systems should be coordinated. The "Storm Drainage" chapter of the AASHTO Model Drainage Manual contains guidance on recommended values for cross slopes. DESIGN STORM The design storm for bridge deck drainage shall not be less than the storm used for design of the pavement drainage system of the adjacent roadway, unless otherwise specified. TYPE, SIZE AND NUMBER OF DRAINS The number of deck drains should be kept to a minimum consistent with hydraulic requirements. In the absence of other applicable guidance, for bridges where the highway design speed is less than 45 MPH, the size and number of deck drains should be such that the spread of deck drainage does not encroach on more than one-half the width of any designated traffic lane. For bridges where the highway design speed is not less than 45 MPH, the spread of deck drainage should not encroach on any portion of the designated traffic lanes. For bridges with adjacent pedestrian sidewalk, the spread of deck drainage should not encroach on any portion of the adjacent designated traffic lanes. Gutter flow should be intercepted at cross slope transitions to prevent flow across the bridge deck. DISCHARGE FROM DECK DRAINS Deck drains shall be designed and located such that surface water from the bridge deck or road surface is directed away for the bridge superstructure elements and the substructure. Consideration should be given to: � � � � � A minimum 4.0-IN projection below the lowest adjacent superstructure component, Location of pipe outlets such that a 45-degree cone of splash will not touch structural components. Use of free drops or slots in parapets wherever practical and permissible, Use of bends not greater than 45 degrees, and Use of cleanouts.
Runoff from bridge decks and deck drains shall be disposed of in a manner consistent with environmental and safety requirements.
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Consideration should be given to the effect of drainage systems on bridge aesthetics. For bridges where free drops are not feasible, attention should be given to the design of the outlet piping system to: � � Minimize clogging and other maintenance problems, and Minimize the intrusive effect of the piping on the bridge symmetry and appearance.
Free drops should be avoided where runoff creates problems with traffic, rail, or shipping lanes. Riprap or pavement should be provided under the free drops to prevent erosion.
DRAINAGE OF STRUCTURES Cavities in structures where there is a likelihood for entrapment of water shall be drained at their lowest point. Decks and wearing surfaces shall be designed to prevent the ponding of water, especially at deck joints. For bridge decks with nonintegral wearing surfaces or stay-in-place forms, consideration shall be given to the evacuation of water that may accumulate at the interface.
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Arizona Department of Transportation
Bridge Group
SECTION 3- LOADS AND LOAD FACTORS
Chapter SCOPE � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � TYPES OF LOADS � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Dead Loads � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Shortening � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Box Girder Deck Forms � � � � � � � � � � � � � � � � � � � � � � � Differential Settlement � � � � � � � � � � � � � � � � � � � � � � � � Future Wearing Surface � � � � � � � � � � � � � � � � � � � � � � Wearing Surface � � � � � � � � � � � � � � � � � � � � � � � � � � � � Live Load & Impact � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Longitudinal Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Centrifugal Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Wind Loads � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Thermal Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Stream Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 1 � Groundline Variations Due to Scour � � � � � � � Lateral Earth Pressure � � � � � � � � � � � � � � � � � � � � � � � � � � � Earthquake � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 2 � Map of Horizontal Acceleration at Bedrock for Arizona � � � � � � � � � � � � � � � � � � � � � � � � � � � �� � � � � � � � DISTRIBUTION OF LOADS � � � � � � � � � � � � � � � � � � � � � � � � Longitudinal Beams (Girders) � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete Box Girders� � � � � � � � � � � � � � � � � � � � � � � � � � � � Transverse Beam (Floorbeams) � � � � � � � � � � � � � � � � � � � � � � � � Multi-beam Decks� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete Slabs � Reinforced Perpendicular to Traffic (Slab on Stringer) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete Slabs � Reinforced Parallel to Traffic (Slab Span) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Page 3 3 3 3 3 4 4 4 4 5 5 5 5 5 8 8 8 10 11 11 12 12 12 12 12 Issue Date 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02
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Concrete Slabs � Reinforced Both Ways� � � � � � � � � � � � � � � � Timber Flooring, Composite Wood � Concrete Members and Glued Laminated Timber Decks� � � � � � � � � Steel Grid Floors� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Spread Box Girders� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Live Load Distribution� � � � � � � � � � � � � � � � � � � � � � � � � � � LOAD COMBINATIONS � � � � � � � � � � � � � � � � � � � � � � � � � � � �
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SCOPE
This section contains guidelines to supplement provisions of Section 3 of the AASHTO Specifications which specifies minimum requirements for loads and forces, the limits of their application, load factors, and load combinations used for the design of new bridges. The load provisions may also be applied to the structural evaluation and modification of existing bridges. In accordance with the applicable provisions of the AASHTO Specifications, the Service Load Design method (Allowable Stress Design) shall be used for the design of all members except columns, sound barrier walls and bridge railings. Columns and sound barrier walls shall be designed by the Strength Design method (Load Factor Design). Bridge railing design for new bridges shall be based on the AASHTO LRFD Bridge Design Specifications. For load applications and distributions for specific bridge types, refer to the following sections.
TYPES OF LOADS
Loads shall be as specified in Section 3 of AASHTO except as clarified or modified in these guidelines. AASHTO loading specifications shall be the minimum design criteria used for all bridges.
Dead Loads (AASHTO 3.3)
The dead load shall consist of the weight of entire structure, including the roadways, curbs, sidewalks, railing. In addition to the structure dead loads, superimposed dead loads such as pipes, conduits, cables, stay-in-place forms and any other immovable appurtenances should be included in the design. SHORTENING Dead load should include the elastic effects of prestressing (pre or post-tensioned) after losses. The long-term effects of shrinkage and creep on indeterminate reinforced concrete structures may be ignored, on the assumption that forces produced by these processes will be relieved by the same processes. BOX GIRDER DECK FORMS Where deck forms are not required to be removed, an allowance of 5-10 lb/ft2 for form dead load shall be included.
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DIFFERENTIAL SETTLEMENT
(AASHTO 3.3.2.1)
Differential settlement shall be considered in the design when indicated in the Geotechnical Report. The Geotechnical Report should provide the magnitude of differential settlement to be use in the design. Differential settlement shall be considered the same as temperature and shrinkage forces and included in Group IV, V and VI load combinations. FUTURE WEARING SURFACE (AASHTO 3.3.3) All new structures shall be designed to carry an additional dead load of 25 pounds per square foot from curb to curb of roadway to allow for a future wearing surface. This load is in addition to any wearing surface, which may be applied at the time of construction. The weight of the future wearing surface shall be excluded from the dead load for deflection calculations. WEARING SURFACE (AASHTO 3.3.5) The top �" of the deck shall be considered as a wearing surface. The weight of the �" wearing surface shall be included in the dead load but the �" shall not be included in the depth of the structural section for all strength calculations including the deck, superstructure and the pier cap, where appropriate.
Live Load & Impact (AASHTO 3.4 - 3.8, 3.11, 3.12)
The design live load shall consist of the appropriate truck or lane loading in accordance with AASHTO 3.7.3. As a minimum, all bridges in Arizona will be designed for HS20-44 loading. In addition, bridges supporting Interstate highways, or other highways which carry heavy truck traffic, will be designed for Alternative Military Loading (AASHTO 3.7.4). The lane loading or standard truck shall be assumed to occupy a width of 10 feet. These loads shall be placed in 12-foot wide design traffic lanes, spaced across the entire bridge roadway width measuring between curbs. Fractional parts of design lanes shall not be used, but roadway width from 20 to 24 feet shall have two design lanes each equal to one-half the roadway width. The traffic lanes shall be replaced in such numbers and positions on the roadway, and the loads shall be placed in such positions within their individual traffic lanes, so as to produce the maximum stress in the member under consideration. Where maximum stresses are produced in any member by loading with three or more traffic lanes simultaneously, the live load may be reduced by a probability factor as covered in AASHTO 3.12. This would apply to members such as transverse floor beams, truss, and two-girder bridges, pier caps, pier columns or any member that has been loaded more than two traffic lanes. This does not apply to deck slab or longitudinal beams designed for fractional wheel loads since less than three traffic lanes will produce the maximum stress. Generally, a reduction factor will be applied in the substructure design for multiple loadings. An impact factor shall be applied to the live load in accordance with AASHTO 3.8. The live load stresses for the superstructure members resulting from the truck or lane loading on the
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superstructure, shall be increased by an allowance for dynamic, vibratory and impact effect. Impact should be included as part of the loads transferred from the superstructure to the substructure, but shall not be included in loads transferred to the footing nor to those parts of piles or columns that are below ground (AASHTO 3.8.1-3.8.2).
Longitudinal Forces (AASHTO 3.9)
Provision shall be made for the effect of a longitudinal force of 5 percent of the live load in all lanes carrying traffic headed in the same direction without impact.
Centrifugal Forces (AASHTO 3.10)
Centrifugal forces are included in all groups which contain vehicular live load. They act 6 feet above the roadway surface and are significant when curve radii are small or columns are long. They are radial forces induced by moving trucks. See AASHTO 3.10.1, Equation (3-2) for force equation.
Wind Loads (AASHTO 3.15)
Wind loads shall be applied according to Section 3.15 of the Standard Specifications.
Thermal Forces (AASHTO 3.16)
Thermal movement and forces shall be based on the following mean temperatures and temperature ranges. Elevation (ft) Mean (oF) Up to 3000 70 3000 - 6000 60 Over 6000 50 Concrete Rise (oF) Fall (oF) 30 40 30 40 35 45 Steel Rise (oF) Fall (oF) 60 60 60 60 70 80
The effects of differential temperature between the top slab and bottom slab of concrete box girder bridges is normally not considered. However, when approval is obtained for structures which warrant such consideration, the following temperature ranges should be used. DL + Diff Temp DL + LL + I + Diff Temp Delta = 18 degrees Delta = 9 degrees
Stream Forces(AASHTO 3.18.1)
A Bridge Hydraulics Report as outlined in Section 2 shall be produced by Roadway Drainage Section or a consultant, when appropriate, for all stream crossings. The designer should review the Bridge Hydraulics Report for a full understanding of
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waterway considerations. The report should contain as a minimum the following information for both the critical flow and superflood conditions. � � � � � � High water elevation Mean Velocity Scour Elevations (General and Local) Angle of attack Required bank protection Special drainage considerations
For design for the most critical flow and the superflood condition, the following criteria shall be used unless more severe criteria are recommended in the Bridge Hydraulics Report. � Design calculations of stream forces on piers over natural water courses shall assume a 2 foot increase in pier width per side due to blockage by debris with a shape factor k = 1.40 for the first 12 feet of depth of flow. For flows with depths greater than 12 feet, only the top 12 feet shall be assumed blocked by debris with lower sections using the actual pier width and a shape factor in accordance with AASHTO. For uncased drilled shafts, a 20% increase in diameter should be assumed to account for possible oversizing of the hole and any irregular shape. The force distribution on the pier shall be assumed to vary linearly from the value at the water surface to zero at the bottom of the scour hole as described in AASHTO. When the clear distance between columns or shafts is 16 feet or greater, each column or shaft shall be treated as an independent unit for stream forces and debris. When the clear distance is less than 16 feet the greater of the two following criteria shall be used: 1) Each column or shaft acting as an independent unit or 2) All columns or shafts acting as one totally clogged unit. The mean main channel velocity for the appropriate flow condition shall be used in calculating the stream forces. The water surface elevation shall be the high water elevation for the appropriate flow condition. A minimum angle of attack of 15 degrees shall be assumed. Scour may be categorized into two types: general and local. General scour is the permanent loss of soil due to degradation or mining while local scour is the temporary loss of soil during a peak flow. Local scour may consist of two types: contraction scour and local pier or abutment scour. Contraction scour occurs uniformly across the bridge opening when the waterway opening of the bridge causes a constriction in the stream width. Local pier and abutment scour occurs locally at substructure units due to the turbulence caused by the presence of the substructure unit. Bridge foundation units outside the highwater prism need not be designed for scour or stream forces. Spread footing bearing elevations shall be minimum 5 ft. below the channel thalweg
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elevation. Tip of drilled shaft elevations shall be minimum 20 ft. below the channel thalweg elevation unless in rock sockets. � Bridges over natural watercourses shall be investigated for four different streambed ground lines. Refer to Figure 1 for an illustration of these cases. 1. Case 1 is the as-constructed stream cross section. For this case, the bridge shall be designed to withstand the forces from the AASHTO Groups I to VII load combinations. 2. Case 2 represents the long-term dry streambed cross section (i.e. the as-constructed stream cross section minus the depth of the general scour). For this case, the bridge shall be designed to withstand the same forces as for case 1. Bridges need only be designed for Seismic Forces for the case of general scour. The requirements contained in AASHTO 4.4.5.2 need not be met. 3. Case 3 represents the streambed cross section condition for the most critical design flow. Abutment protection is designed to withstand this event and abutments may be assumed to be protected from scour for this condition. Piers will experience the full general and critical flow local scour. For this case, the bridge shall be designed to withstand the forces from the AASHTO Groups I to VI load combinations. 4. Case 4 represents the streambed cross section conditions for the superflood condition. For this case, all bank protection and approach embankments are assumed to have failed. Abutments and piers should be designed for the superflood scour assuming all substructure units have experienced the maximum scour simultaneously. For this case, the bridge shall be designed to withstand the following forces: DL + SF + 0.5W. For members designed using the WSD Method an allowable overstress of 140% shall be used. For members designed using the LFD Method a gamma factor of 1.25 shall be used.
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FIGURE 1
GROUNDLINE VARIATIONS DUE TO SCOUR
Lateral Earth Pressure (AASHTO 3.20.1)
For backfills compacted in conformance with the AASHTO Standard Specifications, active pressure for unrestrained walls should be calculated using an internal angle of friction of 34 degrees unless recommended otherwise in the Geotechnical Report.
Earthquakes (AASHTO 3.21)
The Standard Specifications for Highway Bridges shall be used for the seismic design of all new structures. However, the Seismic Acceleration Map, Figure 1-5, contained in AASHTO Division I-A Seismic Design shall not be used to determine the Acceleration Coefficient A. A seismic map for Arizona developed through the Arizona Transportation Research Center is contained in Report Number FHWA-AZ 92-344. This map provides horizontal accelerations in rock with 90% probability of not being exceeded in 50 years considering the effects of local faults. This map shall be used for all designs. A reduced
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copy of this map is included in Fig. 2 for information purposes. A full size map may be obtained by contacting Bridge Technical Section at (602) 712-7910 and should be used in actual designs. All new or widened bridge designs shall consider some form of vertical restraints. Vertical restraints shall be provided for all expansion seat abutments except for multispan continuous box girder bridges with integral piers. Vertical restraints shall be provided between all substructure and superstructure units for steel and precast prestressed girder bridges. When required, the vertical restraints shall be designed for a minimum force equal to 10 percent of the contributing dead load unless the Standard Specifications, Division I-A Seismic Design require a higher value. For Seismic Performance Category A Bridges, horizontal restrainers for hinges shall be designed for a force equal to 0.25 x DL of the smaller of the two frames with the column shears due to EQ deducted. For Seismic Performance Category B, C and D bridges, horizontal restrainers for hinges shall be designed in accordance with the Standard Specifications, Division I-A Seismic Design.
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FIGURE 2
MAP OF HORIZONTAL ACCELERATION AT BEDROCK FOR ARIZONA
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DISTRIBUTION OF LOADS
Loads shall be distributed as specified in Section 3 of AASHTO except as clarified or modified in these guidelines. Truck wheel loads are delivered to a flexible support through compressible tires, which make it very difficult to define the area of the bridge deck significantly influenced. Computerized grid systems and finite element programs can come close to reality, but they are complicated to apply and are limited by mesh or element size and by the accuracy with which the mechanical properties of the composite materials can be modeled. These two- or three dimensional problems are reduced to one dimension through various empirical distribution factors given in the AASHTO Standard Specifications. These distribution factors have been derived from research involving physical testing and/or computerized parameter studies. In order to simplify the design procedure, the number of variables was reduced to a minimum consistent with safety and reasonable economy, according to the judgment of the AASHTO Subcommittee on Bridges and Struct

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Arizona Department of Transportation
SECTION 1: SECTION 2: SECTION 3: SECTION 4: SECTION 5: SECTION 6: SECTION 7: SECTION 8: SECTION 9: SECTION 10: SECTION 11: SECTION 12: SECTION 13: SECTION 14: SECTION 15: SECTION 16:
GENERAL GENERAL DESIGN AND LOCATION FEATURES LOAD AND LOAD FACTORS STRUCTURAL ANALYSIS AND DESIGN METHODS CONCRETE STRUCTURES STEEL STRUCTURES ALUMINUM STRUCTURES WOOD STRUCTURES DECKS AND DECK SYSTEM FOUNDATIONS AND SUBSTRUCTURES RETAINING WALLS AND SOUND BARRIER WALLS CULVERTS AND BURIED STRUCTURES RAILINGS JOINTS AND BEARINGS TRAFFIC STRUCTURES BRIDGE CONSTRUCTION
Arizona Department of Transportation
Bridge Group
SECTION 1- GENERAL
Chapter PURPOSE � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � STRUCTURE IDENTIFICATION � � � � � � � � � � � � � � � � � � � � � � � � Bridge Definition � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Structure Name � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Structure Number � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Station� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Route and Milepost � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � BRIDGE DESIGN PHASES � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � General � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Initial Design � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 1 � Initial Bridge Study Title Sheet � � � � � � � � � � � Figure 2 � Initial Bridge Study Report Body � � � � � � � � � Figure 3 � Initial Bridge Study Concept Sketch � � � � � � � Preliminary Design � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Preliminary Bridge Selection Report � � � � � � � � � � � � Bridge Over Waterways� � � � � � � � � � � � � � � � � � � � � � � Widenings/Rehabilitation � � � � � � � � � � � � � � � � � � � � � Approval � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Bridge Selection Report � � � � � � � � � � � � � � � � � � � � � � � FHWA Approval� � � � � � � � � � � � � � � � � � � � � � � � � � � � � Final Design � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Stage III� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Stage IV � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � PS & E Submittal � Stage V � � � � � � � � � � � � � � � � � � � Bid Advertisement Date � � � � � � � � � � � � � � � � � � � � � � � � � � Bid Opening � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Post Design Services � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � BRIDGE PROJECT ENGINEER'S RESPONSIBILITY � � � General � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Page 3 3 3 3 4 4 5 5 5 5 8 9 10 11 11 12 12 13 13 13 13 14 14 14 14 14 14 15 15 Issue Date 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01
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Selection of Bridge Project Engineers� � � � � � � � � � � � � � � � Duties of Bridge Project Engineers � � � � � � � � � � � � � � � � � � � � CONSULTANT REVIEW PROCEDURES � � � � � � � � � � � � � � � � General � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Documentation � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Reviews � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 30% Submittal � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 60% Submittal � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 95% Submittal � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 100% Submittal� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Project Review � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � COMPUTING APPROXIMATE QUANTITIES � � � � � � � � � � � General Guidelines � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 1 - Approximate Quantities � � � � � � � � � � � � � � � � � � Table 2 - Sample Approximate Quantities for Concrete Reinforcing Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 3 - Weights in lbs of Deformed Reinforcing Bars Table 4 - Weights of � " Spirals per Vertical Foot � � � � � Structural Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 5 - Sample Approximate Quantities for Reinforcing Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Table 6 � Sample Approximate Quantities for Structural Steel � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Inclusion List for Structural Steel � � � � � � � � � � � � � � � � � � Table 7 � Structural Steel Plate Weight Increase � � � � � � Table 8 � Weight of Stud Shear Connectors � � � � � � � � � � Table 9 � Weights in lbs of Welds per Linear Foot (45O fillet weld) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Exclusion List for Structural Steel � � � � � � � � � � � � � � � � � � Structural Steel (Miscellaneous) � � � � � � � � � � � � � � � � � � � � Structural Excavation � � � � � � � � � � � � � � � � � � � � � � � � � � � � Structure Backfill � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 10 � Structural Excavation Payment Limit � � � � � Figure 11 � Structure Backfill Payment Limit � � � � � � � � Drilled Shafts � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Driven Piles � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 12 � Length of Piling � � � � � � � � � � � � � � � � � � � � � � � Precast Prestressed Concrete Members � � � � � � � � � � � � � � Miscellaneous Items � � � � � � � � � � � � � � � � � � � � � � � � � � � � � �
15 16 17 17 17 18 18 18 19 19 19 20 20 20 21 22 23 24 24 25 26 27 28 28 28 29 29 29 30 30 32 33 34 35 36 37 38
7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 7/16/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01 9/24/01
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PURPOSE
The purpose of these Guidelines is to document ADOT Bridge Group design criteria and to provide guidance on interpretations of the various AASHTO publications and other documents as related to highway bridges and appurtenant structures. The Guidelines are intended to be used for general direction. It will continue to be the responsibility of the designer to ensure that these guidelines are applied properly and modified where appropriate with the necessary approvals. The guidelines should be used with judgment to ensure that the unique aspects of each particular design are properly considered.
STRUCTURE IDENTIFICATION
The procedures for structure identification are established by the National Bridge Inspection Standards. Refer to the Recording and Coding Guide for the Structure Inventory and Appraisal of the Nation's Bridges prepared by FHWA and the Arizona Structure Inventory prepared by ADOT Bridge Management Section.
Bridge Definition
"A 'bridge' is defined as a structure including supports erected over a depression or an obstruction, as water, highway or railway and having a track or passageway for carrying traffic or other moving loads and having an opening measured along the center of the roadway of more than 20 feet between undercopings of abutments or springlines of arches or extreme ends of openings for multiple boxes; it may include multiple pipes, where the clear distance between openings is less than half of the smaller contiguous opening."
Structure Name
Names of State bridges are assigned by the Bridge Management Section Leader. Structures are named in accordance with the kind of facility that goes under or over the principal route. A traffic interchange structure will have "T.I." as part of the name. Overpasses carrying one-way traffic will also include the direction of traffic as part of the name. The name is limited to a 20 digit field. Term Bridge Overpass Underpass Traffic Interchange (T.I.) Description The term "bridge" is usually reserved for structures over water courses or canyons. A structure carrying the principal route over a highway, street or railroad. A structure which provides for passage of the principal route under a highway, street, railroad or other feature. An overpass or underpass is also called a T.I. if on and
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Viaduct Tunnel Pedestrian Overpass Pedestrian Underpass
off ramps are provided to the intersecting roadway. A structure of some length carrying a roadway over various features such as streets, waterways or railroads. A structure carrying a roadway through a hill or mountain. A structure carrying a pedestrian walkway over a roadway. A structure which provides for passage of a pedestrian walkway under a roadway.
Structure Number
Each defined 'bridge' has a unique number assigned by the Bridge Management Section according to the group of numbers allotted to each maintenance responsibility. Twin or parallel structures are numbered individually if there is an open median. Structure number identification remains unique and permanent to that structure. The structure number will be retired only for structures totally removed, for one of two twin structures where the median is closed by subsequent construction or for transfer between state and local agency jurisdiction. The structure numbers allotted to each maintenance responsibility category are as follows: Structure Number 0001-2999 3000-3999 4000-7999 8000 and above Maintenance Responsibility Category State jurisdiction bridges Federal jurisdiction bridges State jurisdiction culverts Local jurisdiction bridges and culverts
Station (Principal Route)
The station identification of the structure is located along a construction centerline of the principal route on or under the structure as determined from the State Highway System Log. For overpass structures with the principal route on the structure, the beginning bridge station is used which is located at the backwall of abutment 1. For underpass structures with the principal route under the structure, use the station of the point of intersection between the principal route under and the construction centerline on the structure. For culvert structures, under 20 feet use the station of the point of intersection between the principal route and the construction centerline of the culvert. For culvert structures 20 feet and over, use the station of the beginning backwall.
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Route and Milepost
The principal route and milepost identification shall be shown on all plan sheets. The milepost of the route on or under the structure is determined from the Arizona Highway System Milepost Log. The milepost is recorded to the nearest 1/100th of a mile as calculated from the Station (Principal Route).
BRIDGE DESIGN PHASES General
The design of a major structure consists of three design phases: Initial Design, Preliminary Design and Final Design. The Initial Design Phase consists of examination of bridge concepts including type, length and depth. These studies may be prepared prior to submitting a project in the 5 Year Program or in conjunction with the preparation of a Project Assessment (PA) or a Design Concept Report (DCR). These studies will form the basis for the Bridge Selection Report and provide the Geotechnical Engineer with sufficient information to order one or two initial borings to be used in providing a preliminary foundation recommendation. The Preliminary Design Phase consists of two distinct activities. The first activity is the Alternatives and Selection Study Phase where different bridge types with varying span lengths, girder spacings and foundation types are investigated along with other structure types and comparative cost estimates. This activity results in a Preliminary Bridge Selection Report which will be distributed for comments and provide the Geotechnical Engineer with the required information to perform a final drilling program and produce a Bridge Geotechnical Report. The second activity consists of finalizing the Bridge Selection Report based on the final Bridge Hydraulics Report and Bridge Geotechnical Report. The Final Design Phase consists of performing the required design calculations, drawing the plan sheets, preparing a final estimate and preparing the Special Provisions for bridge related items.
Initial Design
The Initial Design Phase consists of developing an Initial Bridge Study. The purpose of the Initial Bridge Study is to: � � Provide the structure depth for setting profile grades. Establish the best possible early cost estimate.
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� � � �
Allow for Bridge Group input in scoping activity. Familiarize Bridge Design with upcoming projects. Describe and document the design assumptions used in the development stage. Document the existing bridge condition, including waterway adequacy if appropriate, for bridge replacement projects.
Up to three studies could be made during this phase; one as a study to determine a project's merits prior to becoming a project to be included in the 5 Year Program, one as for development of the Project Assessment and one as information for development of a Design Concept Report. The purpose of these studies is to develop as early as possible a feasible type of structure, cost and design restrictions for each site. The completeness of the study will depend on when the study is performed. For example, a study for a Design Concept Report should have more information than a pre-programmed study. Each of the three possible study times should be viewed as part of a continuous effort to define the scope of the project with each new study building on the previous study. An Initial Bridge Study will be performed for all major bridge projects to be nominated to the 5 Year Program by the Bridge Group or the Districts prior to nomination. For existing bridges, this study will be performed in conjunction with the Bridge Candidate List for the Highway Bridge Replacement and Rehabilitation Program to help determine which candidate bridges should be programmed for replacement. Close coordination with Bridge Management Section, Drainage Section and the Districts will be required. These studies will examine the condition of qualified existing bridges to determine which bridges should be developed into replacement projects. An Initial Bridge Study will be performed for all major structures during the Project Assessment Stage. If a study has already been performed, the original study should be updated and enhanced based on whatever additional data has become available. The project manager will initiate the process and establish the schedule for this activity. When concensus can not be reached at the Project Assessment Stage, the project will require a Design Concept Report. Previous studies should be used as a basis for a new Initial Bridge Study; however, additional alignments will be investigated requiring additional studies of alternates. On projects involving rehabilitation or replacement of existing bridges, the project manager shall identify the historical significance of the bridge before concept studies are initiated. The historical significance is determined from the Arizona Structure Inventory and involves a variety of characteristics: the bridge may be a particularly unique example of the history of engineering; the crossing itself might be significant; the bridge might be associated with a historical property or area; or historical significance could be derived
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from the fact the bridge was associated with significant events or circumstances. A copy of the Arizona Structure Inventory is on file. For projects where existing bridges are involved, a thorough review of the Bridge Inspection File and coordination with Bridge Management Section will be required. The major study emphasis will be to verify the condition of the existing bridge, to develop concepts for replacement including the feasibility of widening or rehabilitating versus replacement, and to determine project costs. At this stage, bridge costs will be based on square foot of deck. These Initial Bridge Studies are concepts based on the best available information and are subject to change. Assumptions used as the basis for these studies should be clearly documented and items that are likely to be subject to change as more information is obtained should be identified. An Initial Bridge Study will consist of a title sheet, report body and concept sketch. Refer to figures 1,2 and 3 for a sample of format and contents.
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FIGURE 1 INITIAL BRIDGE STUDY TITLE SHEET
ARIZONA DEPARTMENT OF TRANSPORTATION BRIDGE GROUP BRIDGE DESIGN SECTION A, B or C
INITIAL BRIDGE STUDY DATE
HIGHWAY NAME PROJECT NAME PROJECT NUMBER TRACS NUMBER
BRIDGE NAME EXISTING STRUCTURE NUMBER MILEPOST
Prepared by
Date
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FIGURE 2 INITIAL BRIDGE STUDY REPORT BODY
GENERAL: This section should contain a general discussion of the project including location of the bridge and purpose of the study. EXISTING ROADWAY: This section should contain a discussion of the existing roadway geometrics including identification of any deficiencies. EXISTING DRAINAGE: This section should contain a discussion of the hydrology and hydraulics of the site including design Q, high water, capacity, bank protection and scour vulnerability of existing bridge. EXISTING BRIDGE: This section should contain a discussion of the bridge geometrics and condition of the existing bridge including: rating of the deck and superstructure, adequacy of existing bridge rail, whether bridge is designed for a future wearing surface, the seismic vulnerability, condition of the bearings, expansion joints and approach slabs and a recommendation on whether the bridge could be widened or rehabilitated. ALTERNATES: This section should contain a discussion of the various alternates investigated including: structure type, superstructure depth, girder spacing, column type and spacing, foundation alternates, construction phasing, traffic handling and costs.
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FIGURE 3 INITIAL BRIDGE STUDY CONCEPT SKETCH
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Preliminary Design
Preliminary design consists of three distinct activities: (1) performing concept studies and producing a Preliminary Bridge Selection Report, (2) development of preliminary plans for the chosen alternate and finalizing the Bridge Selection Report and (3) obtaining FHWA approval of the Bridge Selection Report.
Preliminary Bridge Selection Report
The Preliminary Bridge Selection Report consists of performing concept studies as a continuation of the Initial Bridge Study. These studies involve investigating alternate superstructure and foundation types including variations of span length, structure depth and number of girders to determine the best bridge type and arrangement for a particular site. This portion of the Preliminary Design Phase is an iterative phase where assumptions must be made and later verified or modified during the process. Detailed indepth design should not be performed in this phase unless it is necessary to confirm the adequacy of the concept. When performing the concept studies the following shall be considered as a minimum: � � � � Cost Constructability Maintenance Aesthetics
Sketches should be made of the various alternates. During this phase, both the vertical and horizontal clearances should be checked to ensure that the adequate clearances are provided. Inadequate vertical clearance will necessitate a change in either profile grade or superstructure depth while inadequate horizontal clearance may necessitate a change in span length. During this phase, the geotechnical aspects of the site should be considered since the foundation type and associated cost may influence the type of bridge selected. Since a preliminary drilling program has been performed following the Initial Design Phase, a preliminary Bridge Geotechnical Report will be available for use in determining foundation type and costs. During this phase, the traffic requirements must be investigated including any detours or phasing requirements. These details should be worked out with Traffic Design. The need for a deck protection system and type of system will be determined during this phase. Details of the system should be worked out with Bridge Management Section.
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Bridges over Waterways
For waterway crossings, the Preliminary Design Phase will require coordination with Drainage Section or the drainage consultant, as appropriate. The designer should obtain the Bridge Hydraulics Report and thoroughly review the contents before starting the concept study phase.
Widenings/Rehabilitation
On projects involving widenings, in addition to the requirements for new bridges, the following items should be investigated during the Preliminary Design Phase: � Comments from the environmental process concerning the historical significance of the structure, if any, should be added to the discussion of the historical significance contained in the Initial Bridge Study. The existing structure should be checked for structural adequacy. The main superstructure girders should be checked for adequacy to carry the appropriate design live load. If the bridge does not rate sufficiently high, the girders may need to be strengthened, respaced or replaced, or a new bridge may be recommended. The deck slab should also be checked. Decks that are severely overstressed may require replacement. The condition of the existing deck joints should be investigated. If the existing joints are not working or are inadequate, they may require replacement. The condition of the existing bearings should be investigated. If the existing bearings are not performing adequately, they may require modification or replacement. This can affect cost and traffic phasing. The condition of existing diaphragms on steel girder bridges should be investigated. The need for this or any other repair work should be determined at this time. Welded diaphragms have caused past problems. The existing foundations should be checked for adequacy against predicted scour and if inadequate, appropriate means taken to upgrade the foundations against failure. The existing waterway opening should be checked to ensure that it can properly handle the design frequency event. Assessment of scour vulnerability and condition of bank protection should be included. The need for adding approach slabs and/or anchor slabs, if missing, should be investigated. The adequacy of existing bridge rail, that would be left in place, should be investigated.
�
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The need for earthquake retrofit measures should be determined. Existing or proposed utility conflicts should be investigated.
When the above items have been investigated, preliminary design can proceed by studying alternatives. Possible alternatives include: widening to one side, widening symmetrically on both sides or replacing the bridge with a new structure. Approximate costs based on preliminary quantities and unit costs associated with each solution will be required.
Approval
When a decision has been reached concerning the type of bridge selected, the justification for the choice along with comparative cost estimates and sketches should be summarized in the Preliminary Bridge Selection Report. This report should be submitted to the Section Leader and State Bridge Engineer for approval. When approved, the Preliminary Bridge Selection Report should be presented to the Geotechnical Engineer for their use in conducting a final geotechnical investigation.
Bridge Selection Report
The finalization of the Bridge Selection Report is the second activity in the preliminary design phase. This activity involves incorporating the contents of the final Bridge Hydraulics Report and final Bridge Geotechnical Report into the Preliminary Bridge Selection Report to produce a final Bridge Selection Report and develop the preliminary plans for the approved alternative. The preliminary plans consist of the General Plan and the General Notes and Quantities Sheets. The preliminary plans are not considered complete until the Bridge Hydraulics Report and Bridge Geotechnical Report are received and incorporated in the plans. There may be up to a six month delay between ordering drilling and receiving a recommendation.
FHWA Approval
This activity consists of obtaining FHWA approval of the Bridge Selection Report for Federal Aid Projects. Upon receipt of FHWA approval, the Preliminary Plans are considered complete and the Final design of the bridge may start.
Final Design
The Final Design Phase consists of performing the required structural analysis for the bridge and drawing the required details for the development of the construction drawings, producing the final cost estimate and preparing the Special Provisions. This phase should not start until the preliminary documents have been approved.
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Final design consists of two phases: the first phase consists of designing and producing drawings for the Stage III document submittal, the second phase consists of completing the Stage IV final documents.
Stage III
This activity involves completion of most of the structural analysis; some of the drawings, a preliminary cost estimate with quantities and unit costs; and any required special provisions. This phase will also include reviewing the 60% project plans, submitting comments and attending the office and/or field review.
Stage IV
This activity consists of incorporating the Stage III review comments in the design, completing the structural analysis and drawings, producing final quantities and a final cost estimate, and reviewing the Special Provisions. When the project design is complete and quantities are calculated, a cost estimate shall be made. Unit costs may be obtained from the latest copy of the Unit Cost Summary and from the Bridge Group Bridge Costs Records. Unit prices should be adjusted for site location, size of project and other pertinent data.
PS & E Submittal - Stage V
The Plans, Specifications and Estimate (PS & E) Submittal is the final review of the project. This submittal shall be made when requested by the Control Desk. Complete plans and final quantities should always be finished by this date.
Bid Advertisement Date
The Bid Advertisement Date is the date the project is advertised. The Active Project Status Report refers to this date as the Bid Date. When requested by the Control Desk, the complete, signed and stamped tracings shall be sent to the Control Desk for printing of the bid sets.
Bid Opening
The Bid Opening is the date when the bids are opened. This activity normally ends the design phase. The construction contract for the project is then awarded at the next scheduled Arizona Transportation Board meeting.
Post Design Services
Post design services include the following activities: attending partnering sessions, making plan changes as a result of errors or changed conditions, approving falsework and shop drawing submittals, supervising structural steel inspections, producing as-built plans and reviewing the final as-built structural drawings for evaluation of design work and study for improvement.
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BRIDGE PROJECT ENGINEER'S RESPONSIBILITY General
Bridge Project Engineers are to be assigned to all new projects in which structure plans are required. The Bridge Engineer or Bridge Designer will be designated as the Bridge Project Engineer when the project study report or final Project Assessment becomes available and will be responsible for project delivery for all structure related items thru PS & E completion and subsequent construction contract completion. Bridge Project Engineers are hereby given the authority and will be responsible for seeing that all Bridge Group design features comprising the PS & E package on projects are delivered on time, within budget, and in conformance with standards, to meet established schedules. Such features include structure plans for bridges, earth retaining structures, hydraulic structures, highway sign and lighting support structures, specifications for structures, and cost estimates for structures. Bridge Project Engineers may also have responsibility for coordinating work efforts for completion of all work tasks if they are assigned as Project Managers according to the provisions of the Project Management process.
Selection of Bridge Project Engineers
Bridge Designers and Bridge Engineers interested in being selected as Bridge Project Engineers must obtain their Professional Engineer License and they must exhibit a majority of the following skills or traits: � � � � � � � � Has developed the technical skill. Gets along well with people. Is an innovator. Has initiative. Communicates effectively. Is practical. Has leadership abilities and will make decisions. Keeps abreast of technical developments.
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� �
Has an understanding of ADOT policies and procedures. Understands the importance of project deadlines.
Duties of Bridge Project Engineers
A Bridge Project Engineer is assigned to support or act as the Project Leader or Project Manager and to direct the specific work effort assigned to Bridge Group. The duties of the Bridge Project Engineer shall include: � � � � Remain completely knowledgeable about the specific project tasks assigned. Direct the project work activities assigned. Coordinate with the project leader or project manager, as appropriate, on schedule, budget and quality control. Provide input for establishing a project's network model and on a continuous basis, provide input to update schedule data in the Management Scheduling and Control System. Review all preliminary reports for the project. Review bridge maintenance records for widening and rehabilitation projects. Review prior commitments to other agencies and coordinate commitments with ADOT policies. Direct preparation of Bridge Selection Reports and submit for approval as required. Coordinate structural details and design features within the project. Conduct meetings with designers and detailers as required. Work closely with other groups and services so that decisions in these areas are timely and consistent throughout the project. Attend scheduled progress meetings and site visits and provide information as required. Submit structure plans, special provisions and cost estimate on schedule. Coordinate all bridge construction liaison activities such as shop drawing review, construction modifications and final as-building.
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CONSULTANT REVIEW PROCEDURES General
This section is intended to provide procedures to be followed by the Bridge Design Sections in their review of consultant designs. The intent of these procedures is to produce consultant designs which have the same appearance (format and content) as ADOT Bridge Group in-house designs and to promote consistency among the three Design Sections and the consultants. A Project Engineer will be assigned to each consultant review project. Large bridge projects will usually also have a designer assigned to the project to assist in the review.
Documentation
Reviews will be performed on scoping documents such as Project Assessments or Design Concept Reports whether prepared by a consultant or ADOT. Reviews will also be performed on consultant bridge designs at the 30%, 60%, 95% and 100% stages. All submittals shall be stamped with the date received and a log book of all consultant review submittals shall be kept by each Section. The log shall track the type of review document, the date each submittal is received, the date when comments are due, and the date comments are returned. An official project review file, consisting of hard grey filing folders, and a working file should be maintained for each project. The official project review file shall be organized the same as for in-house designs with a title sheet, an index and correspondence on the left side and review comments on the right side. The working file shall contain the submittal documents, special provisions and reviewer calculations. Review comments should be returned to the project manager and be submitted on a Bridge Group Comment Review Form. A copy of all review comments shall be kept in the Official Project Review File.
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Reviews
At each review stage, the reviewer should verify that all previous comments have been resolved and are properly reflected in the new submittal. When all old comments have been resolved, the old submittal documents may be discarded. Reviews should be made to ensure that each submittal meets the requirements for the appropriate submittal stage. Reviews should also verify major features of the design but should not include number by number calculation checks. Calculations will not usually be submitted unless requested by the reviewer.
30% Submittal
For a 30% submittal, the following items should be included as a minimum: � � � � � General Plan Bridge Selection Report Cost Estimate Final Bridge Geotechnical Report Final Bridge Hydraulics Report
Review of 30% submittals should be limited to ensuring that the proper bridge type, span lengths, widths and structure depth have been selected. An independent preliminary superstructure analysis should be performed to verify the structure depth. The reviewer should also check for consistency between the Geotechnical and Hydraulics Reports as related to the recommended foundation type. The General Plan and General Notes and Quantity Sheets should be complete except for the quantity box. Unit costs should be reviewed and bid items compared to the Approximate Quantity Manual guidelines.
60% Submittal
For a 60% submittal the following items should be included as a minimum: � � � � � � 60% Bridge Plans Superstructure completed Boring logs completed Substructure started Draft Bridge Special Provisions Cost Estimate including Bid Items, Item numbers and unit costs
Review of 60% submittals should consist of ensuring that major bridge items have not changed from the 30% submittal and that all 30% comments have been incorporated into the plans. The deck and superstructure designs should be checked. The superstructure plan sheets should be complete. The reviewer should verify that the substructure is consistent with the Bridge Geotechnical Report.
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95% Submittal
For a 95% submittal the following items should be included as a minimum: � � � 95% Bridge Plans Final Special Provisions Final Cost Estimate
Review of 95% submittals should consist of ensuring that 60% review comments have been incorporated into the plans. A review of the substructure for clarity and completeness should be made.
100% Submittal
The 100% submittal should be reviewed to ensure that the 95% comments have been incorporated into the plans and that all outstanding issues have been resolved.
Project Review
In addition to the review of bridge documents, the reviewer should review the project plans for consistency between the bridge plans and the civil and traffic plans. Items such as roadway profiles, bearings and width should be reviewed. Other items which should be reviewed include the appropriate use of Standard Drawings including such design features as CBCs, retaining walls, pipe headwalls and tubular sign supports. Items involving special design should be given oversight review. Such items might include light poles, sign supports, tubular signs, FMS, retaining walls, CBCs, miscellaneous structural items, sound walls and Barrier Summary Sheets.
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COMPUTING APPROXIMATE QUANTITIES General Guidelines
The Purpose of this section is to establish guidelines and methods for the computation of approximate quantities for bridges and related structures and to identify the proper Bid Item Numbers. Quantities are used in the preparation of the Engineer's estimates and in establishing bid schedules. Contractors use the quantities as a basis for making contract bids. Box Culvert quantities are to be computed in accordance with the Reinforced Concrete Box Culvert Manual. Sample approximate quantities sheets, Table 1, are provided to show the accuracy required for calculations. A second set of computations for each structure should be made by a checker independently of the original calculations. This rigorous check is needed to minimize error and prevent the omission of a major item. Small sketches of the items being calculated should be shown on the calculation sheets when the item description is not completely self-explanatory. The effort made to keep the calculation sheets easy to follow will be invaluable during back-checking. This section identifies commonly used Standard Bid Items with Descriptions, Materials, Construction Requirements, Methods of Measurements and Basis of Payments in accordance with ADOT Standard Specifications. If a new Bid Item is required, a Special Provision will have to be written. Contracts and Specifications Section should be contacted for the proper number to be used. If the structure drawings do not give enough information to compute the quantities, it is evident they are deficient and should be revised.
Concrete
The total figure of each item entered in the approximate quantities table as superstructure, pier or abutment is to be rounded to the nearest C.Y. The degree of accuracy required in deriving this total is outlined on Table 2, titled "Sample Approximate Quantities for Concrete". In cases where the designer has used more than one class or strength of concrete, caution should be exercised so that each part of the item figured is grouped in the proper class and strength of concrete.
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TABLE 1 APPROXIMATE QUANTITIES
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TABLE 2 SAMPLE APPROXIMATE QUANTITIES FOR CONCRETE ARIZONA DEPARTMENT OF TRANSPORTATION
APPROXIMATE QUANTITIES TRACS NO.: STATION PROJ. NO.: CLASS "S" f'c = psi STRUCT. BKFL. STRUCTURE NAME NB/EB
SHEET 1 OF 3 DATE: 3-15-2001 SB/WB BY ABC CHKD DEF OTHER: STRUCTURAL EXCAVATION
FOR: Superstructure-Class `S' Concrete
ITEM DESCRIPTION Class "S" f'c=3000 Parapet "A" Curb "B" UNIT DEPTH
(ft)
UNIT WIDTH
(ft)
UNIT LENGTH
(ft)
NO OF UNITS
(PER ITEM)
TOTAL
CU. FT REVISION
1.500 0.750
0.920 1.250
160.000 160.000
1 1
2 2
442 300 742 / 27=27 c. y.
Class "S" f'c=4500 Deck "C" Girders-Inter. "D" Girders-ends "D" Diaph. @abut. "E" Diaph.-Inter. "E"
0.542 3.167 3.167 2.250 2.167
41.333 1.167 1.167 1.292 0.833
160.000 48.000 25.080 37.170 4.830
1 7 7 1 6 ROUND TO NEAREST CUBIC FOOT.
1 2 2 2 2
3,584 2,484 1,298 216 105 7,687 / 27 c. y. = 285 c. y.
CARRY TO THREE DECIMAL PLACE ACCURACY.
ROUND TO NEAREST CUBIC YARD (TO BE COMPARED WITH CHECK SET).
IT IS RECOMMENDED THAT SMALL SKETCHES BE DRAWN OF PARTS BEING FIGURED.
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Bid Item Numbers for concrete quantities vary based on the specific concrete strength. If a concrete strength not shown is required, Bid Item Number 6010010 should be used. A list of Bid Item Numbers, Items and Units for various concrete strengths follows: ITEM NO. 6010001 6010002 6010003 6010004 6010005 6010006 6010007 6010010 IT E M STRUCTURAL CONCRETE (CLASS S) (F'c=2500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=3000PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=3500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=4000PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=4500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=5000PSI) STRUCTURAL CONCRETE (CLASS S) (F'c=5500PSI) STRUCTURAL CONCRETE (CLASS S) (F'c= ) UNIT CY CY CY CY CY CY CY CY
Reinforcing Steel
The total accumulated figure for each listed Item (Abutment, Pier, Superstructure, etc.) used for reinforcing steel in the approximate quantities table is rounded to the nearest 5 pounds. The following items are omitted from reinforcing steel weights: � � Round smooth bars or bolts. Reinforcing in piles or reinforcing extending into abutments or piers from piles or drilled shafts. For reinforcing transitioning from a drilled shaft to a column refer to Drilled Shafts Section. Reinforcement not shown on the project drawings required for anchorage zone recess blocks, duct ties and grillage assemblies as recommended by the posttensioning system used.
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The length of each item of reinforcement not detailed on the drawings is figured to the nearest 3 inches. An amount of 2 feet is added for any lap not detailed. A lap is figured for every 40 running feet of bar. As an example, a bar required to be 90 feet in length would have a length of 4 feet added to it for 2 laps unless detailed for 46 feet or more. For lapped ends of loops, a total of 8 inches is considered adequate for all sizes of bars. Section 5, Table 1, 2 and 3 give the additional length of bar needed for end hooks on stirrups, dowels, etc. according to the size of the bars in consideration. Table 3, below, is given for the weights of standard deformed reinforcing bars.
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TABLE 3 WEIGHTS IN LBS OF DEFORMED REINFORCING BARS
SIZE W E I GHT SIZE W E I GHT #2 .167 #8 2.670 #3 .376 #9 3.400 #4 .668 #10 4.303 #5 1.043 #11 5.313 #6 1.502 #14 7.65 #7 2.044 #18 13.60
A special Table 4, shown below, is given for weight of �" diameter spiral reinforcing for round concrete columns according to the diameter, cover and pitch. TABLE 4 WEIGHTS OF �" SPIRALS PER VERTICAL FOOT
Col. Dia. (Ft.) 7'-0
Clear Cover (inches) 2 3 6 2 3 6 2 3 6 2 3 6 2
3 55.6 54.2 50.0 51.4 50.0 45.8 47.2 45.8 41.6 43.0 41.6 37.4 38.8
3� 47.7 46.5 42.9 44.1 42.9 39.3 40.5 39.3 35.7 36.9 35.7 32.1 33.3
4 41.7 40.7 37.5 38.6 37.5 34.4 35.4 34.4 31.2 32.3 31.2 28.1 29.1
4� 37.1 36.1 33.3 34.3 33.3 30.5 31.5 30.5 27.7 28.7 27.7 24.9 25.9
Pitch (inches) 5 5� 33.4 32.5 30.0 30.8 30.0 27.5 28.3 27.5 25.0 25.8 25.0 22.5 23.3 30.3 29.6 27.1 28.0 27.1 25.0 25.8 25.0 22.7 23.5 22.7 20.4 21.2
6 27.8 27.1 25.0 25.7 25.0 22.9 23.6 22.9 20.8 21.5 20.8 18.7 19.4
9 18.6 18.2 16.8 17.3 16.8 15.4 15.9 15.4 14.0 14.5 14.0 12.6 13.1
12 14.1 13.7 12.7 13.0 12.7 11.6 12.0 11.6 10.6 11.0 10.6 9.6 9.9
6'-6
6'-0
5'-6
1-24
5'-0
3 6 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6 2 3 6
37.4 33.2 34.6 33.2 29.0 30.4 29.0 24.8 26.2 24.8 20.6 22.0 20.6 16.4 17.8 16.4 12.2 13.6 12.2 8.0
32.1 28.5 29.7 28.5 24.9 26.1 24.9 21.3 22.5 21.3 17.7 18.9 17.7 14.1 15.3 14.1 10.5 11.7 10.5 6.9
28.1 24.9 26.0 24.9 21.8 22.8 21.8 18.6 19.7 18.6 15.5 16.5 15.5 12.3 13.4 12.3 9.2 10.2 9.2 6.0
24.9 22.2 23.1 22.2 19.4 20.3 19.4 16.6 17.5 16.6 13.8 14.7 13.8 11.0 11.9 11.0 8.2 9.1 8.2 5.4
22.5 19.9 20.8 19.9 17.4 18.3 17.4 14.9 15.7 14.9 12.4 13.2 12.4 9.9 10.7 9.9 7.3 8.2 7.3 4.8
20.4 18.1 18.9 18.1 15.8 16.6 15.8 13.5 14.3 13.5 11.3 12.0 11.3 9.0 9.7 9.0 6.7 7.4 6.7 4.4
18.7 16.6 17.3 16.6 14.5 15.2 14.5 12.4 13.1 12.4 10.3 11.0 10.3 8.2 8.9 8.2 6.1 6.8 6.1 4.0
12.6 11.3 11.7 11.3 9.9 10.4 9.9 8.6 9.0 8.6 7.2 7.6 7.2 5.9 6.3 5.9 4.6 5.0 4.6 3.5
9.6 8.6 8.9 8.6 7.6 7.9 7.6 6.6 6.9 6.6 5.6 5.9 5.6 4.6 4.9 4.6 3.7 4.0 3.7 3.0
4'-6
4'-0
3'-6
3'-0
2'-6
2'-0
Special attention is called to the sample approximate quantities for weights on Table 5, which shows the required accuracy for computation of reinforcing weights. As illustrated in the sample, a short description of the item being figured will be beneficial for comparing quantities between estimator and checker. Quantities for epoxy coated reinforcing steel shall be separated from regular reinforcing steel quantities. A list of Bid Item Numbers, Items and Units for reinforcing steel follows: ITEM NO. 6050002 6050012 ITEM REINFORCING STEEL REINFORCING STEEL (EPOXY COATED) UNIT LB LB
Structural Steel
The total figure for structural steel as entered in the approximate quantities table under the item "Superstructure" is to be rounded to the nearest 5 pounds. The degree of accuracy required in computing this total is outlined on Table 6, titled "Sample Approximate Quantities for Structural Steel".
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Structural steel weights are not figured for concrete structures; that is, structures that are dependent on reinforced or prestressed concrete slabs, girders or beams for their load carrying capacity. The cost of structural steel for these structures is included in the price bid for the concrete or other items. TABLE 5 SAMPLE APPROXIMATE QUANTITIES FOR REINFORCING STEEL
ARIZONA DEPARTMENT OF TRANSPORTATION APPROXIMATE QUANTITIES TRACS NO. STATION SHEET STRUCTURE NAME NORTHERN AVE. UP FOR UNIT WEIGHT
(PER FT)
2 OF 3
PROJ. NO.: I-10-4(24) REINF. STEEL STRUCT. STEEL ITEM DESCRIPTION Cap beam long. Back wall long. Hoops in cap Back wall verticals UNIT SIZE #5 #4 #4 #4
NB/EB SB/WB Abutment #1 NO OF UNIT
(PER ITEM)
DATE 3-15-01 . BY ABC CHKD DEF. NO OF ITEMS 1 1 1 1 Subtotal TOTAL W E IGHT 468 203 321 203 1,195 150 101 238 96 220 126 931 REVISION
UNIT LENGTH
(FT)
1.043 .668 .668 .6 6 8
40.75 38.00 13.00 4.00
11 8 37 76
Wing cap long. Hoop in wing cap Wing long. Wing long. Wing stirrups Parapet verticals
#5 #4 #5 #4 #4 #4
1.043 .668 1.043 .668 .668 .6 6 8
12.00 10.75 9.50 9.50 15.00 4.25
6 7 12 8 11 22
2 2 2 2 2 2 Subtotal
STANDARD WEIGHT FROM TABLE 4 Total ROUND TO NEAREST 3 INCHES UNLESS DETAILED ON PLANS Use 2,126 2,125 lbs.
ROUND TOTAL TO NEAREST 5 LBS.
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TABLE 6 SAMPLE APPROXIMATE QUANTITIES FOR STRUCTURAL STEEL ARIZONA DEPARTMENT OF TRANSPORTATION APPROXIMATE QUANTITIES
TRACS NO.: SHEET OF CHKD
STATION
623+ PROJ. NO. : I-10-4(24) REINF. STEEL STRUCT STEEL FOR UNIT SIZE
STRUCTURE NAME
NB/EB
DATE BY
SB/WB
ITEM DESCRIPTION Main Girders Cover PL@Pier #1 Cover PL@Pier #1 Cover PL@Pier #2 Cover PL@Pier #2 Splices
W36x135 PL 3/8x11 Ends PL 5/8x11 Ends PL �x11�
UNIT WEIGHT (PER FT) 135 14.00 9.56 23.40 15.90 19.60
UNIT LENGTH (FT) 247.16 13.00 1.50 16.00 1.50 2.54
NO OF UNITS (PER ITEM) 5 2 2 2 2 2
NO OF ITEMS 1 10 20 5 10 20
TOTAL WEIGHT 166,833 3,640 574 3,744 477 1,992 REVISION
Bolts in Splices Welds for Cover PL Shear Connector Studs
7/8 f 5/16"Fillet
.924 .1 6 6
204
94 1
20 5
Subtotal
�"fx4" .615
1,737 169 183,622 415 415 481 147 2,391 10,441 1,004 1,086 1 ,155
Subtotal
Stiff PL Welds for above Diaphragms Diaphragms Bolts for above Stiff PL Stiff PL PL � x5 5/16"Fillet [18x42.7 [15x33.9 7/8"f PL �x5 PL 3/8x5 8.5 .1 6 6 42.7 33.9 1.101 12.80 6 .38 2.83 7 .7 8 7.0 7.00 2.80 2 .83 20 114 8 44 114 30 8 1 1 1 1 8 1 8
Exp Joint
3x3x3/8
7.20
28.00
2
2
806
Anchors for above Welds
5/8f � Fillet
1.33 .106
29.00 29.00
1 .167
2 4 Subtotal
Total
Round TOTAL TO NEAREST 5 LBS.
Use
77 2 885 201,629 201,630
Lbs. Lbs.
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Listed below are the items which are to be included or excluded in the total of structural steel:
Inclusion List for Structural Steel
1. Structural steel for use in bridge structures consists of rolled shapes, plate girders, shear connectors, plates, bars, angles and other items as defined in this inclusion list. Areas and weights of steel sections amy be found in the A.I.S.C. Manual of Steel Construction. As shown in the A.I.S.C. Manual, the weight of rolled beams is given in pounds per linear foot. In figuring weight for welded plate girders, it is necessary that each plate differing in width, thickness or length be listed separately. The weight of plates greater than 36 inches in width should be increased by a percentage of the basic weight according to Table7 below. This is to allow for the A.S.T.M. permissible overrun of plates. TABLE 7 STRUCTURAL STEEL PLATE WEIGHT INCREASE EXPRESSED IN PERCENTAGE OF NOMINAL WEIGHT Specified Thickness Inches 3/16 to � excl � to 5/16 " 5/16 to 3/8 " 3/8 to 7/16 " 7/16 to � " � to 5/8 " 5/8 to � " � to 1 " 1 to 2 Incl. Over 36 to 48 Incl 3 2.5 2.3 2 2 2 1.8 1.8 Over 48 to 60 excl 4 3.5 3 2.5 2.3 2 2 2 1.8 60 to 72 to 70 84 excl 4.5 4 3.5 3 2.5 2.3 2 2 2 excl 5 4.5 4 3.5 3 2.5 2.3 2 2 84 to 96 excl 6 5 4.5 4 3.5 3 2.5 2.3 2 96 to 108 excle 7 6 5 4.5 4 3.5 3 2.5 2.3 108 to 120 excl 8 7 6 5 4.5 4 3.5 3 2.5 120 to 132 excl 9 8 7 6 5 4.5 4 3.5 3 132 to 144 excl 9.5 8 7.5 6.5 5.5 4.5 4 3.5 144 to 168 excl 168 and over
9.5 8 7 6 5 4.5 4
9 8 6 6 5.5 4.5
TABLE 8 WEIGHT OF STUD SHEAR CONNECTORS Stud Diameter � 5/8 � 7/8 Weight in pounds per 100 studs having in-place length of 3 in. 4 in. 5 in. 6 in. 7 in. 21.0 27.0 33.0 45.0 39.0 33.6 43.2 52.8 72.0 62.4 49.0 61.5 74.0 99.0 86.5 64.0 81.0 98.0 132.0 115.0
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2. BOLTS - All fasteners shall be high-strength bolts, AASHTO M164 (ASTM A325) or AASHTO M253(ASTM A490). Weights of components, including washers, may be found in the A.I.S.C. Manual of Steel Construction. Add 3% if galvanized. 3. WELDS - The weight of fillet welds shall be included in the weight of structural steel. In Table 9 below, a weight per linear foot is given for different sizes of fillet welds. For butt welds, plug welds, etc. no addition or deduction is made for weight calculations. TABLE 9 WEIGHT IN LBS OF WELDS PER LINEAR FOOT 45 degree fillet weld SIZE WEIGHT SIZE WEIGHT 1/8 .027 5/8 .664 3/ 1 6 .060 11/16 .804 1/ 4 .106 3/4 .956 5/16 .166 13/16 1.12 3/8 .239 7/8 1.30 7/ 1 6 .326 15/16 1.50 1/ 2 .425 1" 1.70 9/16 .538
4. The weight of deck drains should be included in the weight of structural steel for the deck.
Exclusion List for Structural Steel
1. 2. 3. 4. 5. 6. 7. Erection bolts. Pedestrian rail and accessories. Bumper (nose) angles for approach slabs. Steel "H" piling or steel encased in concrete piles. Fabricated steel supports or strengthened sections for erection. Deck joint assemblies. Abutment and pier steel bearings.
Structural Steel (Miscellaneous)
All other structural steel items including rockers, rollers, bearing plates, pins and nuts, plates, shapes for bridge sign supports, corresponding weld metal, nuts and bolts, and similar steel items not covered in other contract items will be measured for payment as structural steel (miscellaneous). Quantities should be separated by grade for structural steel. For steel bridges, A36 steel should be listed under Item No. 6040001 while other grades should be listed under Item No. 6040002 with the appropriate grade filled in with the parenthesis. Structural steel weights are not figured for concrete structures. A list of Bid Item Numbers, Items and units for various structural steel follows:
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ITEM NO. 6040001 6040002 6040003
IT E M STRUCTURAL STEEL STRUCTURAL STEEL ( ) STRUCTURAL STEEL (MISC)
UNIT LB LB LB
Structural Excavation
Each amount of structural excavation as shown in the approximate quantities table for items such as abutments and piers is to be rounded to the nearest 5 cu. Yds. Structural excavation limits for piers are bounded on the sides by vertical planes 1'-6" outside the limits of the footing, by the ground line on the top and the bottom of the footing on the bottom. When neat line excavation is called for on the plans or by the standard, the volume not excavated shall be deducted from the above. Structural excavation for abutments is figured with the same limits as described for pier excavation. In many instances abutments are built on approach fills. The depth of structural excavation into the approach fill is figured from the berm elevation to the bottom of the abutment cap beam and no neat line excavation is figured. For pier footings and abutment cap beams on piles, do not use neat line excavation. Excavation for abutment wings has the same 1'-6" limit as the main cap beam and neat line excavation where applicable. Figure 10, Structural Excavation Payment Limits, is shown for typical conditions. Actual payment limits for each structure shall be included with the structure drawings. A list of Bid Item Numbers, Items and Units for structural excavation follows: ITEM NO. 2030501 IT E M STRUCTURAL EXCAVATION UNIT CY
Structure Backfill
Each amount of structure backfill as shown in the approximate quantities table for items such as abutments and piers is to be rounded to the nearest 5 cubic yards. Structure backfill for abutments is figured as follows: When an abutment falls below the existing ground level, structure backfill is figured within structural excavation limits on the approach slab side of the abutment only. When an abutment is built above the existing ground level, an additional area under the
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approach slab is added. Measuring is to be parallel to the centerline of the roadway. The abutment wings enclose this area. Structure backfill is required for piers only when the pier falls within the roadway prism. When the roadway is on one side of a pier only, structure backfill is figured only on the side of the pier. Figure 11, Structure Backfill Payment Limits, is shown for typical conditions. Actual payment limits for each structure shall be included with the structure drawings. A list of Bid Item Numbers, Items and Units for structure backfill follows: ITEM NO. 2030506 IT E M STRUCTURE BACKFILL UNIT CY
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FIGURE 10
STRUCTURAL EXCAVATION PAYMENT LIMITS.
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FIGURE 11 STRUCTURE BACKFILL PAYMENT LIMITS.
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Drilled Shafts
Drilled shafts are bid by the linear foot. The item for drilled shafts includes the drilling, any casing, the concrete and all reinforcing steel embedded in the shaft. Quantities are rounded to the nearest foot for each sub item such as abutments and piers. Quantities are figured separately for each size and separated into two categories: drilled shafts drilled into rock and drilled shafts drilled into soil. Standard sizes are listed below. For special size shafts use Item Number 6090148 and fill in the specified diameter in inches within the parenthesis. For shafts in rock use Item Number 6091030 and fill in the specified diameter in inches within the parenthesis. A list of Bid Item Numbers, Items and Units for drilled shafts follows: ITEM NO. 6090018 6090024 6090030 6090036 6090042 6090048 6090054 6090060 6090066 6090072 6090078 6090084 6090096 6090148 6091030 IT E M DRILLED SHAFT FOUNDATION (18") DRILLED SHAFT FOUNDATION (24") DRILLED SHAFT FOUNDATION (30") DRILLED SHAFT FOUNDATION (36") DRILLED SHAFT FOUNDATION (42") DRILLED SHAFT FOUNDATION (48") DRILLED SHAFT FOUNDATION (54") DRILLED SHAFT FOUNDATION (60") DRILLED SHAFT FOUNDATION (66") DRILLED SHAFT FOUNDATION (72") DRILLED SHAFT FOUNDATION (78") DRILLED SHAFT FOUNDATION (84") DRILLED SHAFT FOUNDATION (96") DRILLED SHAFT FOUNDATION ( ) DRILLED SHAFTS (ROCK) ( ) UNIT LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF
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Driven Piles
Driven piles consist of H-piles, pipe piles and precast piles. Payment is divided into furnishing the pile, driving the pile and splicing, when required. There is no direct estimate for splicing. When an H-pile is specified other than the four sizes shown, items 6030012 and 6030194 should be used and the size placed in the parenthesis. When driven piles other than H-piles are specified, items 6030194 should be used and the type of pile used placed in the parenthesis. When piles must be driven deeper than specified on the plans to develop their strength, the contractor is paid to splice a new section onto the portion of the pile already driven. The cost equals five times the bid price for furnishing the piles. For quantity and payment purposes, two feet is added to the estimated length of a pile. Refer to Figure 12 for a diagram. A list of Bid Item Numbers, Items and Units for driven piles follows: ITEM NO. 6030003 6030005 6030008 6030010 6030012 6030013 6030190 6030191 6030192 6030193 6030194 6030195 6030303 6030305 6030308 6030310 6030312 6030313 ITEM FURNISHING PILES (STEEL) (HP12x53) FURNISHING PILES (STEEL) (HP12x74) FURNISHING PILES (STEEL) (HP14x89) FURNISHING PILES (STEEL) (HP14x117) FURNISH HP PILES FURNISH PILES ( ) DRIVE HP 12 x 53 PILES DRIVE UP 12 x 74 PILES DRIVE HP 14 x 89 PILES DRIVE HP 14 x 117 PILES DRIVE HP PILES ( ) DRIVE PILES ( ) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030003) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030005) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030008) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030010) SPLICING PILE STEEL (5 TIMES UNIT PRICE OF 6030012) SPLICING PILE (5 TIMES UNIT PRICE OF 6030013) UNIT LF LF LF LF LF LF LF LF LF LF LF LF EA EA EA EA EA EA
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FIGURE 12 LENGTH OF PILING
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Precast Prestressed Concrete Members
Precast prestressed concrete members consist of AASHTO standard or modified I-girders, box beams and voided slabs. The bid items are calculated by the linear foot. The total sum of the lengths of all girders are rounded to the nearest foot. The bid item includes reinforcing, concrete, prestressing strand, anything else embedded in the girder and also includes transportation and erection in place. A list of Bid Item Numbers, Items and Units for these members follows: ITEM NO. 6014950 6014951 6014952 6014953 6014954 6014955 6014956 6014957 6014958 6014959 6014960 6014961 6014962 6014963 6014964 6014965 6014966 6014967 6014968 6014969 6014970 6014971 6014972 6014973 ITEM PRECAST, P/S MEMBER (AASHTO TYPE 2 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 3 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 4 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 5 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 6 GIRDER) PRECAST, P/S MEMBER (AASHTO TYPE 5 MOD. GR.) PRECAST, P/S MEMBER (AASHTO TYPE 6 MOD. GR.) PRECAST, P/S MEMBER (BOX BEAM TYPE BI-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BII-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BIII-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BIV-36) PRECAST, P/S MEMBER (BOX BEAM TYPE BI-48) PRECAST, P/S MEMBER (BOX BEAM TYPE BII-48) PRECAST, P/S MEMBER (BOX BEAM TYPE BII-48) PRECAST, P/S MEMBER (BOX BEAM TYPE BIV-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SI-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SII-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SII-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SIV-36) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SI-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SII-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SIII-48) PRECAST, P/S MEMBER (VOIDED SLAB TYPE SIV-48) PRECAST, P/S MEMBER ( ) UNIT LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF LF
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Miscellaneous Items
A list of miscellaneous Bid Item Numbers, Items and Units follows: ITEM NO. 2020002 2020008 2020009 6010501 6010801 6010831 6011130 6011131 6011132 6011133 6011134 6011371 6011372 6011373 6015101 6015102 6015200 6020001 6041001 6050101 6050201 6060040 6060041 6060042 6060043 6060044 6060045 6060046 6060047 6060048 6060075 6060076 IT E M REMOVE BRIDGE REMOVAL OF STRUCTURAL CONCRETE REMOVAL OF STRUCTURAL CONCRETE BRIDGE REPAIR BRIDGE DECK DRAIN ASSEMBLY GROOVE BRIDGE DECK 32 IN. F-SHAPE BRIDGE CONCRETE BARRIER AND TRANSITION (SD 1.01) 42 IN. F-SHAPE BRIDGE CONCRETE BARRIER AND TRANSITION (SD 1.02) COMBINATION PEDESTRIAN-TRAFFIC BRIDGE RAILING (SD 1.04) PEDESTRIAN FENCE FOR BRIDGE RAILING SD 1.04 (SD 1.05) TWO TUBE BRIDGE RAIL (SD 1.06) APPROACH SLAB (SD 2.01) ANCHOR SLAB-TYPE 1 (SD 2.02) ANCHOR SLAB-TYPE 2 (SD 2.03) RESTRAINERS, VERTICAL EARTHQUAKE (FIXED) RESTRAINERS, VERTICAL EARTHQUAKE(EXPANSION) HIGH-LOAD MULTI-ROTATIONAL BEARINGS PRESTRESSING CAST-IN-PLACE CONCRETE JACKING BRIDGE SUPERSTRUCTURE PLACE DOWELS LOAD TRANSFER DOWELS BRIDGE SIGN STRUCTURE (TUBULAR) (40' TO 70') BRIDGE SIGN STRUCTURE (TUBULAR) (70' TO 94') BRIDGE SIGN STRUCTURE (TUBULAR) (94' TO 106') BRIDGE SIGN STRUCTURE (TUBULAR) (106' TO 130') BRIDGE SIGN STRUCTURE (TUBULAR) (130' TO 142') TUBULAR FRAME SIGN STRUCTURE (TYPE 1F) (SD 9.20) TUBULAR FRAME SIGN STRUCTURE (TYPE 2F) (SD 9.20) TUBULAR FRAME SIGN STRUCTURE (TYPE 3F) (SD 9.20) TUBULAR FRAME SIGN STRUCTURE (TYPE 4F) (SD 9.20) FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 1F) (SD 9.20) FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 2F) (SD 9.20) UNIT LUMP SUM LUMP SUM CY LUMP SUM LS SQ YD LF LF LF LF LF SF SF SF EA EA EA LS LUMP SUM EA EA EA EA EA EA EA EA EA EA EA EA EA
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6060078 6060079 6060131 6060132 6060133 6060134 6060161 6060162 6060247 6060254 6060255 6060256 6060257 6100001 6100011 7320471 7379111 9050430 9100008 9120001 9140136 9140137 9210001
FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 3F) (SD 9.20) FOUNDATION FOR TUBULAR FRAME SIGN STRUCTURE (TYPE 4F) (SD 9.20) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 1C) (SD 9.10) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 2C) (SD 9.10) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 3C) (SD 9.10) TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 4C) (SD 9.10) SIGN STRUCTURE (MEDIAN, TWO SIDED) (SD 9.01) SIGN STRUCTURE (MEDIAN, ONE SIDED) (SD 9.02) FOUNDATION FOR SIGN STRUCTURE (MEDIAN) (SD 9.01 OR SD 9.02) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 1C) (SD 9.10) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 2C) (SD 9.10) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 3C) (SD 9.10) FOUNDATION FOR TUBULAR CANTILEVER SIGN STRUCTURE (TYPE 4C) (SD 9.10) PAINTING STRUCTURAL STEEL PAINT BRIDGE BRIDGE JUNCTION BOX VARIABLE MESSAGE SIGN ASSEMBLY INSTALLATION THRIE BEAM GUARD RAIL TRANSITION SYSTEM (SD 1.03) CONCRETE BARRIER (TEMPORARY BRIDGE) SHOTCRETE SOUND BARRIER WALL (CONCRETE) (SD 8.01) SOUND BARRIER WALL (MASONARY) (SD 8.02) SLOPE PAVING (STD. B-19.20 AND B-19.21)
EA EA EA EA EA EA EA EA EA EA EA EA EA LUMP SUM LUMP SUM EA EA EA LF SQ YD SF SF SQ YD
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Arizona Department of Transportation Bridge Group
SECTION 2 - GENERAL DESIGN & LOCATION FEATURES
Chapter SCOPE DEFINITIONS LOCATION FEATURES Route Location Bridge Site Arrangement Clearances Environment Page Issue Date 2 2 4 4 5 6 9 9 9 9 10 10 10 14 15 16 17 17 17 18 19 23 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99 10/22/99
FOUNDATION INVESTIGATION
General Topographic Studies Safety Serviceability Constructibility Economy Bridge Aesthetics
DESIGN OBJECTIVES
HYDROLOGY AND HYDRAULICS
General Site Data Hydrologic Analysis Hydraulic Analysis Deck Drainage
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SCOPE
This section is intended to provide the Designer with sufficient information to determine the configuration and overall dimensions of a bridge. In recognition that many bridge failures have been caused by scour, hydrology and hydraulics are covered in detail. For a complete discussion of the information presented here, refer to the AASHTO LRFD Bridge Design Specifications, Section 2.
DEFINITIONS
Aggradation : A general and progressive buildup or raising of the longitudinal profile of the channel bed as a result of sediment deposition. Bridge Designer : The design team who produced the structural drawings and supporting documents for the bridge. Clear Zone : An unobstructed, relatively flat area beyond the edge of the traveled way for the recovery of errant vehicles. The traveled way does not include shoulders or auxiliary lanes. Clearance : An unobstructed horizontal or vertical space. Degradation: A general and progressive lowering of the longitudinal profile of the channel bed as a result of long-term erosion. Design Discharge: Maximum flow of water a bridge is expected to accommodate without exceeding the adopted design constraints. Design Flood for Bridge Scour: The flood flow equal to or less than the 100-year flood that creates the deepest scour at bridge foundations. The highway or bridge may be inundated at the stage of the design flood for bridge scour. The worst-case scour condition may occur for the overtopping flood as a result of the potential for pressure flow. Detention Basin: A stormwater management facility that impounds runoff and temporarily discharges it through a hydraulic outlet structure to a downstream conveyance system. Drip Groove: Linear depression in the bottom of components to cause water flowing on the surface to drop.
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Five-Hundred-Year Flood: The flood due to storm and/or tide having a 0.2 percent chance of being equaled or exceeded in any given year. Commonly referred to as the Superflood, used to check the structural adequacy of bridge foundations for that extreme design event. General or Contraction Scour: Scour in a channel or on a floodplain that is not localized at a pier or other obstruction to flow. In a channel, general/contraction scour usually affects all or most of the channel width and is typically caused by a contraction of the flow. Hydraulics : The science that deals with practical applications (as the transmission of energy or the effects of flow) of water or other liquid in motion. Hydrology: The science concerned with the occurrence, distribution, and circulation of water on the earth, including precipitation, runoff, and groundwater. In highway design, the process by which design discharges are determined. Local Scour: Scour in a channel or on a floodplain that is localized at a pier, abutment, or other obstruction to flow. One-Hundred-Year Flood: The flood due to storm and/or tide having a 1 percent chance of being equaled or exceeded in any given year. Overtopping Flood: The flood flow that, if exceeded, results in flow over a highway or bridge, over a watershed divide, or through structures provided for emergency relief. The worst-case scour condition may be caused by the overtopping flood. Stable Channel: A condition that exists when a stream has a bed slope and crosssection that allows its channel to transport the water and sediment delivered from the upstream watershed without significant degradation, aggradation, or bank erosion. Stream Geomorphology: The study of a stream and its floodplain with regard to its land forms, the general configuration of its surface, and the changes that take place due to erosion and the buildup of erosional debris. Superelevation: A tilting of the roadway surface to partially counterbalance the centrifugal forces on vehicles on horizontal curves. Superflood : Any flood or tidal flow with a flow rate greater than that of the 100-year flood but not greater than a 500-year flood. Estimated magnitude equals 1.7 times the 100-year flood. Watershed : An area confined by drainage divides, and often having only one outlet for discharge; the total drainage area contributing runoff to a single point. Waterway: Any stream, river, pond, lake, or ocean.
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Waterway Opening: Width or area of bridge opening at a specified stage, and measured normal to principal direction of flow.
LOCATION FEATURES Route Location
GENERAL The choice of location of bridges shall be supported by analyses of alternatives with consideration given to economic, engineering, social, and environmental concerns as well as costs of maintenance and inspection associated with the structures and with the relative importance of the above-noted concerns. Attention, commensurate with the risk involved, shall be directed toward providing for favorable bridge locations that: � � � � Fit the conditions created by the obstacle being crossed; Facilitate practical cost effective design, construction, operation, inspection and maintenance; Provide for the desired level of traffic service and safety; and Minimize adverse highway impacts.
WATERWAY AND FLOODPLAIN CROSSINGS Waterway crossings shall be located with regard to initial capital costs of construction and the optimization of total costs, including river channel training works and the maintenance measures necessary to reduce erosion. Studies of alternative crossing locations should include assessments of: � � � � The hydrologic and hydraulic characteristics of the waterway and its floodplain, including channel stability and flood history. The effect of the proposed bridge on flood flow patterns and the resulting scour potential at bridge foundations; The potential for creating new or augmenting existing flood hazards; and Environmental impacts on the waterway and its floodplain.
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Bridges and their approaches on floodplains should be located and designed with regard to the goals and objectives of floodplain management, including; � � � � � � Prevention of uneconomic, hazardous, or incompatible use and development of floodplains; Avoidance of significant transverse and longitudinal encroachments, where practicable; Minimization of adverse highway impacts and mitigation of unavoidable impacts, where practicable; Consistency with the intent of the standards and criteria of the National Flood Insurance Program, where applicable; Long-term aggradation or degradation; and Commitments made to obtain environmental approvals
It is generally safer and more cost effective to avoid hydraulic problems through the selection of favorable crossing locations than to attempt to minimize the problems at a later time in the project development process through design measures. Experience at existing bridges should be part of the calibration or verification of hydraulic models, if possible. Evaluation of the performance of existing bridges during past floods is often helpful in selecting the type, size, and location of new bridges.
Bridge Site Arrangement
GENERAL The location and the alignment of the bridge should be selected to satisfy both on-bridge and under-bridge traffic requirements. Consideration should be given to possible future variations in alignment or width of the waterway, highway, or railway spanned by the bridge. Where appropriate, consideration should be given to future addition of mass-transit facilities or bridge widening. TRAFFIC SAFETY Protection of structures Consideration shall be given to safe passage of vehicles on or under a bridge. The hazard to errant vehicles within the clear zone should be minimized by locating obstacles at a safe distance from the travel lanes.
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Pier columns or walls for grade separation structures should be located in conformance with the clear zone concept as contained in Chapter 3 of the AASHTO Roadside Design Guide. Where the practical limits of structure costs, type of structure, volume and design speed of through traffic, span arrangement, skew, and terrain make conformance with the Roadside Design Guide impractical, the pier or wall should be protected by the use of guardrail or other barrier devices. The guardrail or other device should, if practical, be independently supported, with its roadway face at least 2.0 FT from the face of pier or abutment, unless a rigid barrier is provided. The intent of providing structurally independent barriers is to prevent transmission of force effects from the barrier to the structure to be protected. The face of the guardrail or other device should be at least 2.0 FT outside the normal shoulder line. Protection of Users Railings shall be provided along the edges of structures conforming to the requirements of Section 13 of AASHTO LRFD Bridge Design Specifications. All protective structures shall have adequate surface features and transitions to safely redirect errant traffic. Geometric Standards Requirements of the AASHTO publication A Policy on Geometric Design of Highways and Streets shall either be satisfied or exceptions thereto shall be justified and documented. Width of travel lanes and shoulders shall meet the requirements established by the roadway engineer. Road Surfaces Road surfaces on a bridge shall be given antiskid characteristics, crown, drainage, and superelevation in accordance with A Policy on Geometric Design of Highways and Streets.
Clearances
NAVIGATIONAL Permits for construction of a bridge over navigable waterways shall be obtained from the U.S. Coast Guard and/or other agencies having jurisdiction. Navigational clearances, both vertical and horizontal, shall be established in cooperation with the U.S. Coast Guard. The Colorado River is the only navigable waterway in Arizona with U.S. Coast Guard jurisdiction. Certain reservoirs have bridges over navigable waterway passage with other agencies having jurisdiction.
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VERTICAL CLEARANCE AT STRUCTURES The following are minimum vertical clearance standards for highway traffic structures, pedestrian overpasses, railroad overpasses, tunnels and sign structures. Lesser clearances may be used only under very restrictive conditions, upon individual analysis and with the approval of the Assistant State Engineer-Roadway Group. HIGHWAY TRAFFIC STRUCTURES The design vertical clearance to structures passing over all roadways shall be at least 16'-6 over the entire roadway width, including auxiliary lanes and shoulders. An allowance of 6 inches is included to accommodate future resurfacing. This allowance may be waived if the roadway under the structure is surfaced with portland cement concrete. Consideration should be given to providing 16'-6 clearance at interchange structures having large volumes of truck traffic and at other structures over highways carrying very high traffic volumes, regardless of the highway system classification. PEDESTRIAN OVERPASSES Because of their lesser resistance to impacts, the minimum design vertical clearance to pedestrian overpasses shall be 17'-6 regardless of the highway system classification. An allowance of 6 inches is included to accommodate future resurfacing. TUNNELS The minimum design vertical clearance for tunnels shall be at least 16'-6 for freeways, arterials and all other State Highways and at least 15'-6 for all other highways and streets. SIGN STRUCTURES Because of their lesser resistance to impacts, the minimum design vertical clearance to sign structures shall be 18'-0 regardless of the highway system classification. An allowance of 6 inches is included to accommodate future resurfacing. HORIZONTAL CLEARANCE AT STRUCTURES The bridge width shall not be less than that of the approach roadway section, including shoulders or curbs, gutters, and sidewalks.
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No object on or under a bridge, other than a barrier, should be located closer than 4.0 FT to the edge of a designated traffic lane. The inside face of a barrier should not be closer than 2.0 FT to either the face of the object or the edge of a designated traffic lane. RAILROAD OVERPASS Structures designed to pass over a railroad shall be in accordance with standards established and used by the affected railroad in its normal practice. These overpass structures shall comply with applicable federal, state, county, and municipal laws. Structures over railways shall provide a minimum clearance of 23 feet above top of rail, except that overhead clearance greater than 23 feet may be approved when justified on the basis of railroad electrification. No additional allowance shall be provided for future track adjustments. Regulations, codes, and standards should, as a minimum, meet the specifications and design standards of the American Railway Engineering Association, the Association of American Railroads, and AASHTO. Requirements of the individual railroads in Arizona are contained in regulations published by the Arizona Corporation Commission. Attention is particularly called to the following chapters in the Manual for Railway Engineering (AREA 1991): � � � � � Chapter 7 � Timber Structures, Chapter 8 � Concrete Structures and Foundations, Chapter 9 � Highway-Railroad Crossings, Chapter 15 � Steel Structures, and Chapter 18 � Clearances.
The provisions of the individual railroads and the AREA Manual should be used to determine: � � � � � Clearances, Loadings, Pier protection, Waterproofing, and Blast protection.
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Environment
The impact of a bridge and its approaches on local communities, historic sites, wetlands, and other aesthetically, environmentally, and ecologically sensitive areas shall be considered. Compliance with state water laws; federal and state regulations concerning encroachment on floodplains, fish, and wildlife habitats; and the provisions of the National Flood Insurance Program shall be assured. Stream geomorphology, consequences of riverbed sour, and removal of embankment stabilizing vegetation, shall be considered. Stream, i.e., fluvial, geomorphology is a study of the structure and formation of the earth's features that result from the forces of water. For purposes of this section, this involves evaluating the stream's potential for aggradation, degradation, or lateral migration.
FOUNDATION INVESTIGATION General
A subsurface investigation, including borings and soil tests, shall be conducted in accordance with the provisions of AASHTO to provide pertinent and sufficient information for the design of substructure units. The type and cost of foundations should be considered in the economic and aesthetic studies for location and bridge alternate selection. For bridge replacement or rehabilitation, existing geotechnical data may provide valuable information for initial studies.
Topographic Studies
Current topography of the bridge site shall be established via contour maps and photographs. Such studies shall include the history of the site in terms of movement of earth masses, soil and rock erosion, and meandering of waterways.
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DESIGN OBJECTIVES Safety
The primary responsibility of the Bridge Designer shall be providing for the safety of the public.
Serviceability
DURABILITY Materials The contract documents shall call for quality materials and for the application of high standards of fabrication and erection. Structural steel shall be self-protecting, or have long-life coating systems. Reinforcing bars and prestressing strands in concrete components, which may be expected to be exposed to airborne or waterborne salts, shall be protected by an appropriate combination of epoxy and/or composition of concrete, including airentrainment and a nonporous painting of the concrete surface. Prestress strands in cable ducts shall be grouted or otherwise protected against corrosion. Attachments and fasteners used in wood construction shall be of stainless steel, malleable iron, aluminum, or steel that is galvanized, cadmium-plated, or otherwise coated. Wood components shall be treated with preservatives. Aluminum products shall be electrically insulated from steel and concrete components. Protection shall be provided to materials susceptible to damage from solar radiation and/or air pollution. Consideration shall be given to the durability of materials in direct contact with soil, sun and/or water. Self-Protecting Measures Continuous drip grooves shall be provided along the underside of a concrete deck at a distance not exceeding 10.0 IN from the fascia edges. Where the deck is interrupted by a sealed deck joint, all top surfaces of piers and abutments, other than bearing seats, shall have a minimum slope of 5 percent toward their edges. For open deck joints, this minimum slope shall be increased to 15 percent. In the case of open deck joints, the bearings shall be protected against contact with salt and debris.
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Wearing surfaces shall be interrupted at the deck joints and shall be provided with a smooth transition to the deck joint device. INSPECTABILITY Inspection ladders, walkways, catwalks, covered access holes, and provision for lighting, if necessary, shall be provided where other means of inspection are not practical. Where practical, access to allow manual or visual inspection, including adequate headroom in box sections, shall be provided to the inside of cellular components and to interface areas, where relative movement may occur. MAINTAINABILITY Structural systems whose maintenance is expected to be difficult should be avoided. Where the climatic and/or traffic environment is such that the bridge deck may need to be replaced before the required service life, either provisions shall be shown on the contract plans for the replacement of the deck or additional structural resistance shall be provided. Areas around bearing seats and under deck joints should be designed to facilitate jacking, cleaning, repair, and replacement of bearings and joints. Jacking points shall be indicated on the plans, and the structure shall be designed for the jacking forces. Inaccessible cavities and corners should be avoided. Cavities that may invite human or animal inhabitants shall either be avoided or made secure. RIDEABILITY The deck of the bridge shall be designed to allow for the smooth movement of traffic. On paved roads, a structural transition slab should be located between the approach roadway and the abutment of the bridge. Construction tolerances, with regard to the profile of the finished deck, shall be indicated on the plans or in the specifications or special provisions. The number of deck joints shall be kept to a practical minimum. Edges of joints in concrete decks exposed to traffic should be protected from abrasion and spalling. The plans for prefabricated joints shall specify that the joint assembly be erected as a unit, if feasible. Where concrete decks without an initial overlay are used, an additional thickness of 0.5IN to permit correction of the deck profile by grinding, and to compensate for thickness loss due to abrasion will be provided.
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UTILITIES IN STRUCTURES Where utility conflicts exist; water, power, telephone, cable TV and gas lines will be relocated as required for construction of the project. Where it is feasible and reasonable to locate utility lines elsewhere, attachment to structures will not be permitted. Trenching in the vicinity of existing piers or abutments shall be kept a sufficient distance from footings to prevent undercutting of existing footings or to prevent disturbing foundation soils for future foundations. Where other locations prove to be extremely difficult and very costly, utility lines, except natural gas, may be allowed in the structures. Natural gas encroachments will be evaluated under the following policy: A. Cases were gas line attachments to structures will not be considered under any condition: 1. Grade separation structures carrying vehicular traffic on or over freeways. 2. Inside closed cell-type box girder bridges. 3. High pressure transmission lines over 60 psi and/or distribution lines of over 6 inches in diameter. 4. Gas lines over minor waterway crossings where burial is feasible B. Gas line attachments on structures will be considered under the following cases or conditions: 1. Each case will be judged on its own merit with the utilities providing complete justification as to why alternative locations are not feasible. 2. Economics will not be a significant factor considered in the feasibility issue. 3. Open girder type structures across major rivers. 4. Pedestrian or utility bridges where proper vented casings and other safety systems are used. 5. All lines are protected by casements. Provisions for accommodation of relocated and future utilities on structures shall be coordinated through the Utility and Railroad Engineering Section for ADOT projects, or as appropriate, through Statewide Project Management Section and/or a consultant for other projects.
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General Policy Support bracket details and attachments for all utilities will require Bridge Group approval. All approved utilities shall have individual sleeved casings, conduits or ducts as appropriate. All utilities carrying liquids shall be placed inside casing through the entire length of the structure. The casing shall be designed to carry full service pressure so as to provide a satisfactory containment in case the utility is damaged or leaks. Water lines, telephone conduits, power lines, cable TV lines, supports or other related items will not be permitted to be suspended below or attached to the exterior of any new or existing structure. Product lines for transmitting volatile fluids will not be permitted to be attached to or suspended from or placed within any new or existing structure. Manholes or access openings for utilities will not be permitted in bridge decks, webs, bottom slabs or abutment diaphragms. On special major projects, ADOT design costs will be assessed to the company Utility Company Responsibility The utility company is responsible for obtaining necessary information regarding the proposed construction schedule for the project. The company shall submit a request including justification for attaching to the structure and preliminary relocation plans including line weights and support spacing as early as possible but no later than the completion of preliminary structural plans. The company shall submit complete plans and specifications of their proposed installation at least 20 working days prior to the schedule C & S Date. The utility company shall be responsible for the design of all conduits, pipes, sleeves, casings, expansion devices, supports and other related items including the following information: 1. Number and size of conduits for power, telephone and cable TV lines. 2. Size and schedule of carrier pipe for water lines. 3. Size and schedule of sleeved casings. 4. Spacing and details of support brackets.
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5. Expansion device details. 6. Total combined weight of carrier pipe and transmitted fluids, conduits, casings, support brackets, expansion joints and other related items. 7. Design calculations. 8. Submit permit request through the District. Bridge Designer Responsibility The Bridge Designer shall be responsible for the following aspects of the design : 1. Determination of how many lines, if any, the structure can accommodate. 2. Determination of where such lines should be located within a structure. 3. Determination of the size of the access openings and design of the required reinforcing. 4. Identification of installation obstacles related to required sequencing of project. 5. Tracking man-hours associated with utility relocations for cost recovery, when appropriate. Usually utilities will be accommodated by providing individual access openings for casings and sleeves to pass through. Access openings should be 2 inches larger than the diameter of the casings or sleeves and spaced as required by structural considerations. For box girder bridges, access openings should be located as low as possible but no lower than 10 inches above the top of the bottom slab to allow for support brackets to be supported from the bottom slab. Where possible all utilities shall be supported from the bottom slab for box girder bridges. For precast or steel girder bridges, the utilities shall not be placed in the exterior girder bay and they shall be supported from the deck slab, rather than from the diaphragms.
Constructibility
Bridges should be designed in a manner such that fabrication and erection can be performed without undue difficulty or distress and that locked-in construction force effects are within tolerable limits.
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When the method of construction of a bridge is not self-evident or could induce unacceptable locked-in stresses, at least one feasible method shall be indicated in the contract documents. If the design requires some strengthening and/or temporary bracing or support during erection by the selected method, indication of the need thereof shall be indicated in the contract documents. Details that require welding in restricted areas or placement of concrete through congested reinforcing should be avoided. Climatic and hydraulic conditions that may affect the construction of the bridge shall be considered.
Economy
GENERAL Structural types, span lengths, and materials shall be selected with due consideration of projected cost. The cost of future expenditures during the projected service life of the bridge should be considered. Regional factors, such as availability of material, fabrication, location, shipping, and erection constraints, shall be considered. If data for the trends in labor and material cost fluctuation is available, the effect of such trends should be projected to the time the bridge will likely be constructed. Cost comparisons of structural alternatives should be based on long-range considerations, including inspection, maintenance, repair, and/or replacement. Lowest first cost does not necessarily lead to lowest total cost. ALTERNATIVE PLANS In instances where economic studies do not indicate a clear choice, the State Bridge Engineer may require that alternative contract plans be prepared and bid competitively. Designs for alternative plans shall be of equal safety, serviceability, and aesthetic value. Movable bridges over navigable waterways should be avoided to the extent feasible. Where movable bridges are proposed, at least one fixed bridge alternative should be included in the economic comparisons.
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Bridge Aesthetics
Bridges should complement their surroundings, be graceful in form, and present an appearance of adequate strength. Significant improvements in appearance can often be made with small changes in shape or position of structural members at negligible cost. For prominent bridges, however, additional cost to achieve improved appearance is often justified, considering that the bridge will likely be a feature of the landscape for 75 or more years. Engineers should seek more pleasant appearance by improving the shapes and relationships of the structural component themselves. The application of extraordinary and nonstructural embellishment should be avoided. The following guidelines should be considered: � � � Alternative bridge designs without piers or with few piers should be studied during the site selection and location stage and refined during the preliminary design stage. Pier form should be consistent in shape and detail with the superstructure. Abrupt changes in the form of components and structural type should be avoided. Where the interface of different structural types cannot be avoided, a smooth transition in appearance from one type to another should be attained. Attention to details, such as deck drain downspouts, should not be overlooked. The use of the bridge as a support for message or directional signing or lighting should be avoided wherever possible. Transverse web stiffeners, other than those located at bearing points, should not be visible in elevation. For spanning deep ravines, arch-type structures should be preferred.
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The most admired modern structures are those that rely for their good appearance on the forms of the structural components themselves: � � � Components are shaped to respond to the structural function. They are thick where the stresses are greatest and thin where the stresses are smaller. The function of each part and how the function is performed is visible. Components are slender and widely spaced, preserving views through the structure.
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The bridge is seen as a single whole, with all members consistent and contributing to that whole; for example, all elements should come from the same family of shapes, such as shapes with rounded edges. The bridge fulfills its function with a minimum of material and minimum number of elements. The size of each member compared with the others is clearly related to the overall structural concept and the job the component does, and The bridge as a whole has a clear and logical relationship to its surroundings.
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HYDROLOGY AND HYDRAULICS General
Hydrologic and hydraulic studies and assessments of bridge sites for stream crossings shall be completed as part of the preliminary plan development. The detail of these studies should be commensurate with the importance of and risks associated with the structure. Temporary structures for the Contractor's use or for accommodating traffic during construction shall be designed with regard to the safety of the traveling public and the adjacent property owners, as well as minimization of impact on floodplain natural resources. ADOT may permit revised design requirements consistent with the intended service period for, and flood hazard posed by, the temporary structure. Contract documents for temporary structures shall delineate the respective responsibilities and risks to be assumed by ADOT and the Contractor. Evaluation of bridge design alternatives shall consider stream stability, backwater, flow distribution, stream velocities, scour potential, flood hazards, and consistency with established criteria for the National Flood Insurance Program.
Site Data
A site-specific data collection plan shall include consideration of: � � Collection of aerial and/or ground survey data for appropriate distances upstream and downstream from the bridge for the main stream channel and its floodplain; Estimation of roughness elements for the stream and the floodplain within the reach of the stream under study;
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Sampling of streambed material to a depth sufficient to ascertain material characteristics for scour analysis; Subsurface borings; Factors affecting water stages, including high water from streams, reservoirs, detention basins, and flood control structures and operating procedures; Existing studies and reports, including those conducted in accordance with the provisions of the National Flood Insurance Program or other flood control programs; Available historical information on the behavior of the stream and the performance of the structure during past floods, including observed scour, bank erosion, and structural damage due to debris or ice flows; and Possible geomorphic changes in channel flow.
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Hydrologic Analysis
The following flood flows should be investigated, as appropriate, in the hydrologic studies: � � � For assessing flood hazards and meeting floodplain management requirements � the 100-year flood; For assessing risks to highway users and damage to the bridge and its roadway approaches � the overtopping flood and/or the design flood for bridge scour; For assessing catastrophic flood damage at high risk sites � a check flood of a magnitude selected by the Bridge Designer as appropriate for the site conditions and the perceived risk; For investigating the adequacy of bridge foundations to resist scour � the check flood for bridge scour; To satisfy ADOT design policies and criteria � design floods for waterway opening and bridge scour for the various functional classes of highways, as described in the ADOT Roadway Design Guidelines; To calibrate water surface profiles and to evaluate the performance of existing structures � historical floods, and To evaluate environmental conditions � low or base flow information
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Hydraulic Analysis
GENERAL The Bridge Designer shall utilize analytical models and techniques that have been approved by ADOT and that are consistent with the required level of analysis as described in the ADOT Roadway Design Guidelines. STREAM STABILITY Studies shall be carried out to evaluate the stability of the waterway and to assess the impact of construction on the waterway. The following items shall be considered: � � Whether the steam reach is degrading, aggrading, or in equilibrium; For stream crossing near confluences, the effect of the main stream and the tributary on the flood stages, velocities, flow distribution, vertical and lateral movements of the stream, and the effect of the foregoing conditions on the hydraulic design of the bridge; Location of favorable stream crossing, taking into account whether the stream is straight, meandering, braided, or transitional, or control devices to protect the bridge from existing or anticipated future stream conditions; The effect of any proposed channel changes; The effect of aggregate mining or other operations in the channel; Potential changes in the rates or volumes of runoff due to land use changes; The effect of natural geomorphic stream pattern changes on the proposed structure; and The effect of geomorphic changes on existing structures in the vicinity of, and caused by, the proposed structure.
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For unstable streams or flow conditions, special studies shall be carried out to assess the probable future changes to the plan form and profile of the stream and to determine countermeasures to be incorporated in the design, or at a future time, for the safety of the bridge and approach roadways.
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BRIDGE WATERWAY The design process for sizing the bridge waterway shall include: � � The evaluation of flood flow patterns in the main channel and floodplain for existing conditions, and The evaluation of trial combinations of highway profiles, alignments, and bridge lengths for consistency with design objectives.
Where use is made of existing flood studies, their accuracy shall be determined. BRIDGE FOUNDATIONS General The structural, hydraulic, and geotechnical aspects of foundation design shall be coordinated and differences resolved prior to approval of preliminary plans. To reduce the vulnerability of the bridge to damage from scour and hydraulic loads, consideration should be given to the following general design concepts: � Set deck elevations as high as practical for the given site conditions to minimize inundation, or overtopping of roadway approach sections, and streamline the superstructure to minimize the area subject to hydraulic loads and the collection of ice, debris, and drifts. Utilize relief bridges, guide banks, dikes, and other river training devices to reduce the turbulence and hydraulic forces acting at the bridge abutments. Utilize continuous span designs. Anchor superstructures to their substructures where subject to the effects of hydraulic loads, buoyancy, ice, or debris impacts or accumulations. Provide for venting and draining of the superstructure. Where practical, limit the number of piers in the channel, streamline pier shapes, and align pier columns with the direction of flood flows. Avoid pier types that collect ice and debris. Locate piers beyond the immediate vicinity of stream banks. Locate abutments back from the channel banks where significant problems with ice/debris buildup, scour, or channel stability are anticipated, or where special environmental or regulatory needs must be met, e.g., spanning wetlands. Design piers within floodplains as river piers. Locate their foundations at the appropriate depth if there is a likelihood that the stream channel will shift during the life of the structure or that channel cutoffs are likely to occur.
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Where practical, use debris racks to stop debris before it reaches the bridge. Where significant debris buildup is unavoidable, its effects should be accounted for in determining scour depths and hydraulic loads. A majority of bridge failures in the United States and elsewhere are the result of scour. The added cost of making a bridge less vulnerable to damage from scour is small in comparison to the total cost of a bridge failure.
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Bridge Scour As required by Section 3, scour at bridge foundations is investigated for two conditions: � For the design flood for scour, the streambed material in the scour prism above the scour line shall be assumed to have been removed for design conditions. The design flood storm surge, tide, or mixed population flood shall be the more severe of the 100-year events or from an overtopping flood of lesser recurrence interval. For the check flood for scour, the stability of the bridge foundation shall be investigated for scour conditions resulting from a designated flood storm surge, tide, or mixed population flood not to exceed the 500-year event or from an overtopping flood of lesser recurrence interval. Excess reserve beyond that required for stability under this condition is not necessary. The extreme event limit state shall apply.
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If the site conditions, due to debris jams, and low tailwater conditions near stream confluences dictate the use of a more severe flood event for either the design or check flood for scour, the Bridge Designer may use such flood event. Spread footings on soil or erodible rock shall be located beyond the scour potential of the waterway. Spread footings on scour-resistant rock shall be designed and constructed to maintain the integrity of the supporting rock. Deep foundations with footings shall be designed to place the top of the footing below the estimated contraction scour depth where practical to minimize obstruction to flood flows and resulting local scour. Even lower elevations should be considered for pilesupported footings where the piles could be damaged by erosion and corrosion from exposure to stream currents. Where conditions dictate a need to construct the top of a footing to an elevation above the streambed, attention shall be given to the scour potential of the design. When fendering or other pier protection systems are used, their effect on pier scour and collection of debris shall be taken into consideration in the design. The design flood for scour shall be determined on the basis of the Bridge Designer's judgment of the hydrologic and hydraulic flow conditions at the site. The recommended procedure is to evaluate scour due to the specified flood flows and to design the foundation for the event expected to cause the deepest total scour.
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The recommended procedure for determining the total scour depth at bridge foundations is as follows: � � � � Estimate the long-term channel profile aggradation or degradation over the service life of the bridge; Estimate the effects of gravel mining on the channel profile, if appropriate; Estimate the long-term channel plan form changes over the service life of the bridge; As a design check, adjust the existing channel and floodplain cross-sections upstream and downstream of bridge as necessary to reflect anticipated changes in the channel profile and plan form; Determine the combination of existing or likely future conditions and flood events that might be expected to result in the deepest scour for design conditions.; Determine water surface profiles for a stream reach that extends both upstream and downstream of the bridge site for the various combinations of conditions and events under consideration; Determine the magnitude of contraction scour and local scour at piers and abutments; and Evaluate the results of the scour analysis, taking into account the variables in the methods used, the available information on the behavior of the watercourse, and the performance of existing structures during past floods. Also consider present and anticipate future flow patterns and the effect of the flow on the bridge. Modify the bridge design where necessary to satisfy concerns raised by the scour analysis and the evaluation of the channel plan form.
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Foundation designs should be based on the total scour depths estimated by the above procedure, taking into account appropriate geotechnical safety factors. Where necessary, bridge modifications may include: � � � � Relocation or redesign of piers or abutments to avoid areas of deep scour or overlapping scour holes from adjacent foundation elements, Addition of guide banks, dikes, or other river training works to provide for smoother flow transitions or to control lateral movement of the channel, Enlargement of the waterway area, or Relocation of the crossing to avoid an undesirable location.
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Foundations should be designed to withstand the conditions of scour for the design flood and the check flood. In general, this will result in deep foundations. The design of the foundations of existing bridges that are being rehabilitated should consider underpinning if scour indicates the need. Riprap and other scour countermeasures may be appropriate if underpinning is not cost effective. The stability of abutments in areas of turbulent flow shall be thoroughly investigated. Exposed embankment slopes should be protected with appropriate scour countermeasures. ROADWAY APPROACHES TO BRIDGE The design of the bridge shall be coordinated with the design of the roadway approaches to the bridge on the floodplain so that the entire flood flow pattern is developed and analyzed as a single, interrelated entity. Where roadway approaches on the floodplain obstruct overbank flow, the highway segment within the floodplain limits shall be designed to minimize flood hazards. Where diversion of flow to another watershed occurs as a result of backwater and obstruction of flood flows, an evaluation of the design shall be carried out to ensure compliance with legal requirements in regard to flood hazards in the watershed.
Deck Drainage
GENERAL The bridge deck and its highway approaches shall be designed to provide safe and efficient conveyance of surface runoff from the traveled way in a manner that minimizes damage to the bridge and maximizes the safety of passing vehicles. Transverse drainage of the deck, including roadway, bicycle paths, and pedestrian walkways, shall be achieved by providing a cross slope or superelevation sufficient for positive drainage. For wide bridges with more than three lanes in each direction, special design of bridge deck drainage and/or special rough road surfaces may be needed to reduce the potential for hydroplaning. Water flowing downgrade in the roadway gutter section shall be intercepted and not permitted to run into the bridge. Drains at bridge ends shall have sufficient capacity to carry all contributing runoff. In those unique environmentally sensitive instances where it is not possible to discharge into the underlying water course, consideration should be given to conveying the water in a longitudinal storm drain affixed to the underside of the bridge and discharging it into appropriate facilities on natural ground at bridge end. Where feasible, bridge decks should be watertight and all of the deck drainage should be carried to the ends of the bridge.
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A longitudinal gradient on bridges should be maintained. Zero gradients and sag vertical curves should be avoided. Design of the bridge deck and the approach roadway drainage systems should be coordinated. The "Storm Drainage" chapter of the AASHTO Model Drainage Manual contains guidance on recommended values for cross slopes. DESIGN STORM The design storm for bridge deck drainage shall not be less than the storm used for design of the pavement drainage system of the adjacent roadway, unless otherwise specified. TYPE, SIZE AND NUMBER OF DRAINS The number of deck drains should be kept to a minimum consistent with hydraulic requirements. In the absence of other applicable guidance, for bridges where the highway design speed is less than 45 MPH, the size and number of deck drains should be such that the spread of deck drainage does not encroach on more than one-half the width of any designated traffic lane. For bridges where the highway design speed is not less than 45 MPH, the spread of deck drainage should not encroach on any portion of the designated traffic lanes. For bridges with adjacent pedestrian sidewalk, the spread of deck drainage should not encroach on any portion of the adjacent designated traffic lanes. Gutter flow should be intercepted at cross slope transitions to prevent flow across the bridge deck. DISCHARGE FROM DECK DRAINS Deck drains shall be designed and located such that surface water from the bridge deck or road surface is directed away for the bridge superstructure elements and the substructure. Consideration should be given to: � � � � � A minimum 4.0-IN projection below the lowest adjacent superstructure component, Location of pipe outlets such that a 45-degree cone of splash will not touch structural components. Use of free drops or slots in parapets wherever practical and permissible, Use of bends not greater than 45 degrees, and Use of cleanouts.
Runoff from bridge decks and deck drains shall be disposed of in a manner consistent with environmental and safety requirements.
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Consideration should be given to the effect of drainage systems on bridge aesthetics. For bridges where free drops are not feasible, attention should be given to the design of the outlet piping system to: � � Minimize clogging and other maintenance problems, and Minimize the intrusive effect of the piping on the bridge symmetry and appearance.
Free drops should be avoided where runoff creates problems with traffic, rail, or shipping lanes. Riprap or pavement should be provided under the free drops to prevent erosion.
DRAINAGE OF STRUCTURES Cavities in structures where there is a likelihood for entrapment of water shall be drained at their lowest point. Decks and wearing surfaces shall be designed to prevent the ponding of water, especially at deck joints. For bridge decks with nonintegral wearing surfaces or stay-in-place forms, consideration shall be given to the evacuation of water that may accumulate at the interface.
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Arizona Department of Transportation
Bridge Group
SECTION 3- LOADS AND LOAD FACTORS
Chapter SCOPE � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � TYPES OF LOADS � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Dead Loads � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Shortening � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Box Girder Deck Forms � � � � � � � � � � � � � � � � � � � � � � � Differential Settlement � � � � � � � � � � � � � � � � � � � � � � � � Future Wearing Surface � � � � � � � � � � � � � � � � � � � � � � Wearing Surface � � � � � � � � � � � � � � � � � � � � � � � � � � � � Live Load & Impact � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Longitudinal Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Centrifugal Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Wind Loads � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Thermal Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Stream Forces � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 1 � Groundline Variations Due to Scour � � � � � � � Lateral Earth Pressure � � � � � � � � � � � � � � � � � � � � � � � � � � � Earthquake � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Figure 2 � Map of Horizontal Acceleration at Bedrock for Arizona � � � � � � � � � � � � � � � � � � � � � � � � � � � �� � � � � � � � DISTRIBUTION OF LOADS � � � � � � � � � � � � � � � � � � � � � � � � Longitudinal Beams (Girders) � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete Box Girders� � � � � � � � � � � � � � � � � � � � � � � � � � � � Transverse Beam (Floorbeams) � � � � � � � � � � � � � � � � � � � � � � � � Multi-beam Decks� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete Slabs � Reinforced Perpendicular to Traffic (Slab on Stringer) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Concrete Slabs � Reinforced Parallel to Traffic (Slab Span) � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Page 3 3 3 3 3 4 4 4 4 5 5 5 5 5 8 8 8 10 11 11 12 12 12 12 12 Issue Date 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/ 6 / 0 2 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02 8/6/02
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Concrete Slabs � Reinforced Both Ways� � � � � � � � � � � � � � � � Timber Flooring, Composite Wood � Concrete Members and Glued Laminated Timber Decks� � � � � � � � � Steel Grid Floors� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Spread Box Girders� � � � � � � � � � � � � � � � � � � � � � � � � � � � � � Live Load Distribution� � � � � � � � � � � � � � � � � � � � � � � � � � � LOAD COMBINATIONS � � � � � � � � � � � � � � � � � � � � � � � � � � � �
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SCOPE
This section contains guidelines to supplement provisions of Section 3 of the AASHTO Specifications which specifies minimum requirements for loads and forces, the limits of their application, load factors, and load combinations used for the design of new bridges. The load provisions may also be applied to the structural evaluation and modification of existing bridges. In accordance with the applicable provisions of the AASHTO Specifications, the Service Load Design method (Allowable Stress Design) shall be used for the design of all members except columns, sound barrier walls and bridge railings. Columns and sound barrier walls shall be designed by the Strength Design method (Load Factor Design). Bridge railing design for new bridges shall be based on the AASHTO LRFD Bridge Design Specifications. For load applications and distributions for specific bridge types, refer to the following sections.
TYPES OF LOADS
Loads shall be as specified in Section 3 of AASHTO except as clarified or modified in these guidelines. AASHTO loading specifications shall be the minimum design criteria used for all bridges.
Dead Loads (AASHTO 3.3)
The dead load shall consist of the weight of entire structure, including the roadways, curbs, sidewalks, railing. In addition to the structure dead loads, superimposed dead loads such as pipes, conduits, cables, stay-in-place forms and any other immovable appurtenances should be included in the design. SHORTENING Dead load should include the elastic effects of prestressing (pre or post-tensioned) after losses. The long-term effects of shrinkage and creep on indeterminate reinforced concrete structures may be ignored, on the assumption that forces produced by these processes will be relieved by the same processes. BOX GIRDER DECK FORMS Where deck forms are not required to be removed, an allowance of 5-10 lb/ft2 for form dead load shall be included.
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DIFFERENTIAL SETTLEMENT
(AASHTO 3.3.2.1)
Differential settlement shall be considered in the design when indicated in the Geotechnical Report. The Geotechnical Report should provide the magnitude of differential settlement to be use in the design. Differential settlement shall be considered the same as temperature and shrinkage forces and included in Group IV, V and VI load combinations. FUTURE WEARING SURFACE (AASHTO 3.3.3) All new structures shall be designed to carry an additional dead load of 25 pounds per square foot from curb to curb of roadway to allow for a future wearing surface. This load is in addition to any wearing surface, which may be applied at the time of construction. The weight of the future wearing surface shall be excluded from the dead load for deflection calculations. WEARING SURFACE (AASHTO 3.3.5) The top �" of the deck shall be considered as a wearing surface. The weight of the �" wearing surface shall be included in the dead load but the �" shall not be included in the depth of the structural section for all strength calculations including the deck, superstructure and the pier cap, where appropriate.
Live Load & Impact (AASHTO 3.4 - 3.8, 3.11, 3.12)
The design live load shall consist of the appropriate truck or lane loading in accordance with AASHTO 3.7.3. As a minimum, all bridges in Arizona will be designed for HS20-44 loading. In addition, bridges supporting Interstate highways, or other highways which carry heavy truck traffic, will be designed for Alternative Military Loading (AASHTO 3.7.4). The lane loading or standard truck shall be assumed to occupy a width of 10 feet. These loads shall be placed in 12-foot wide design traffic lanes, spaced across the entire bridge roadway width measuring between curbs. Fractional parts of design lanes shall not be used, but roadway width from 20 to 24 feet shall have two design lanes each equal to one-half the roadway width. The traffic lanes shall be replaced in such numbers and positions on the roadway, and the loads shall be placed in such positions within their individual traffic lanes, so as to produce the maximum stress in the member under consideration. Where maximum stresses are produced in any member by loading with three or more traffic lanes simultaneously, the live load may be reduced by a probability factor as covered in AASHTO 3.12. This would apply to members such as transverse floor beams, truss, and two-girder bridges, pier caps, pier columns or any member that has been loaded more than two traffic lanes. This does not apply to deck slab or longitudinal beams designed for fractional wheel loads since less than three traffic lanes will produce the maximum stress. Generally, a reduction factor will be applied in the substructure design for multiple loadings. An impact factor shall be applied to the live load in accordance with AASHTO 3.8. The live load stresses for the superstructure members resulting from the truck or lane loading on the
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superstructure, shall be increased by an allowance for dynamic, vibratory and impact effect. Impact should be included as part of the loads transferred from the superstructure to the substructure, but shall not be included in loads transferred to the footing nor to those parts of piles or columns that are below ground (AASHTO 3.8.1-3.8.2).
Longitudinal Forces (AASHTO 3.9)
Provision shall be made for the effect of a longitudinal force of 5 percent of the live load in all lanes carrying traffic headed in the same direction without impact.
Centrifugal Forces (AASHTO 3.10)
Centrifugal forces are included in all groups which contain vehicular live load. They act 6 feet above the roadway surface and are significant when curve radii are small or columns are long. They are radial forces induced by moving trucks. See AASHTO 3.10.1, Equation (3-2) for force equation.
Wind Loads (AASHTO 3.15)
Wind loads shall be applied according to Section 3.15 of the Standard Specifications.
Thermal Forces (AASHTO 3.16)
Thermal movement and forces shall be based on the following mean temperatures and temperature ranges. Elevation (ft) Mean (oF) Up to 3000 70 3000 - 6000 60 Over 6000 50 Concrete Rise (oF) Fall (oF) 30 40 30 40 35 45 Steel Rise (oF) Fall (oF) 60 60 60 60 70 80
The effects of differential temperature between the top slab and bottom slab of concrete box girder bridges is normally not considered. However, when approval is obtained for structures which warrant such consideration, the following temperature ranges should be used. DL + Diff Temp DL + LL + I + Diff Temp Delta = 18 degrees Delta = 9 degrees
Stream Forces(AASHTO 3.18.1)
A Bridge Hydraulics Report as outlined in Section 2 shall be produced by Roadway Drainage Section or a consultant, when appropriate, for all stream crossings. The designer should review the Bridge Hydraulics Report for a full understanding of
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waterway considerations. The report should contain as a minimum the following information for both the critical flow and superflood conditions. � � � � � � High water elevation Mean Velocity Scour Elevations (General and Local) Angle of attack Required bank protection Special drainage considerations
For design for the most critical flow and the superflood condition, the following criteria shall be used unless more severe criteria are recommended in the Bridge Hydraulics Report. � Design calculations of stream forces on piers over natural water courses shall assume a 2 foot increase in pier width per side due to blockage by debris with a shape factor k = 1.40 for the first 12 feet of depth of flow. For flows with depths greater than 12 feet, only the top 12 feet shall be assumed blocked by debris with lower sections using the actual pier width and a shape factor in accordance with AASHTO. For uncased drilled shafts, a 20% increase in diameter should be assumed to account for possible oversizing of the hole and any irregular shape. The force distribution on the pier shall be assumed to vary linearly from the value at the water surface to zero at the bottom of the scour hole as described in AASHTO. When the clear distance between columns or shafts is 16 feet or greater, each column or shaft shall be treated as an independent unit for stream forces and debris. When the clear distance is less than 16 feet the greater of the two following criteria shall be used: 1) Each column or shaft acting as an independent unit or 2) All columns or shafts acting as one totally clogged unit. The mean main channel velocity for the appropriate flow condition shall be used in calculating the stream forces. The water surface elevation shall be the high water elevation for the appropriate flow condition. A minimum angle of attack of 15 degrees shall be assumed. Scour may be categorized into two types: general and local. General scour is the permanent loss of soil due to degradation or mining while local scour is the temporary loss of soil during a peak flow. Local scour may consist of two types: contraction scour and local pier or abutment scour. Contraction scour occurs uniformly across the bridge opening when the waterway opening of the bridge causes a constriction in the stream width. Local pier and abutment scour occurs locally at substructure units due to the turbulence caused by the presence of the substructure unit. Bridge foundation units outside the highwater prism need not be designed for scour or stream forces. Spread footing bearing elevations shall be minimum 5 ft. below the channel thalweg
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elevation. Tip of drilled shaft elevations shall be minimum 20 ft. below the channel thalweg elevation unless in rock sockets. � Bridges over natural watercourses shall be investigated for four different streambed ground lines. Refer to Figure 1 for an illustration of these cases. 1. Case 1 is the as-constructed stream cross section. For this case, the bridge shall be designed to withstand the forces from the AASHTO Groups I to VII load combinations. 2. Case 2 represents the long-term dry streambed cross section (i.e. the as-constructed stream cross section minus the depth of the general scour). For this case, the bridge shall be designed to withstand the same forces as for case 1. Bridges need only be designed for Seismic Forces for the case of general scour. The requirements contained in AASHTO 4.4.5.2 need not be met. 3. Case 3 represents the streambed cross section condition for the most critical design flow. Abutment protection is designed to withstand this event and abutments may be assumed to be protected from scour for this condition. Piers will experience the full general and critical flow local scour. For this case, the bridge shall be designed to withstand the forces from the AASHTO Groups I to VI load combinations. 4. Case 4 represents the streambed cross section conditions for the superflood condition. For this case, all bank protection and approach embankments are assumed to have failed. Abutments and piers should be designed for the superflood scour assuming all substructure units have experienced the maximum scour simultaneously. For this case, the bridge shall be designed to withstand the following forces: DL + SF + 0.5W. For members designed using the WSD Method an allowable overstress of 140% shall be used. For members designed using the LFD Method a gamma factor of 1.25 shall be used.
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FIGURE 1
GROUNDLINE VARIATIONS DUE TO SCOUR
Lateral Earth Pressure (AASHTO 3.20.1)
For backfills compacted in conformance with the AASHTO Standard Specifications, active pressure for unrestrained walls should be calculated using an internal angle of friction of 34 degrees unless recommended otherwise in the Geotechnical Report.
Earthquakes (AASHTO 3.21)
The Standard Specifications for Highway Bridges shall be used for the seismic design of all new structures. However, the Seismic Acceleration Map, Figure 1-5, contained in AASHTO Division I-A Seismic Design shall not be used to determine the Acceleration Coefficient A. A seismic map for Arizona developed through the Arizona Transportation Research Center is contained in Report Number FHWA-AZ 92-344. This map provides horizontal accelerations in rock with 90% probability of not being exceeded in 50 years considering the effects of local faults. This map shall be used for all designs. A reduced
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copy of this map is included in Fig. 2 for information purposes. A full size map may be obtained by contacting Bridge Technical Section at (602) 712-7910 and should be used in actual designs. All new or widened bridge designs shall consider some form of vertical restraints. Vertical restraints shall be provided for all expansion seat abutments except for multispan continuous box girder bridges with integral piers. Vertical restraints shall be provided between all substructure and superstructure units for steel and precast prestressed girder bridges. When required, the vertical restraints shall be designed for a minimum force equal to 10 percent of the contributing dead load unless the Standard Specifications, Division I-A Seismic Design require a higher value. For Seismic Performance Category A Bridges, horizontal restrainers for hinges shall be designed for a force equal to 0.25 x DL of the smaller of the two frames with the column shears due to EQ deducted. For Seismic Performance Category B, C and D bridges, horizontal restrainers for hinges shall be designed in accordance with the Standard Specifications, Division I-A Seismic Design.
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FIGURE 2
MAP OF HORIZONTAL ACCELERATION AT BEDROCK FOR ARIZONA
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DISTRIBUTION OF LOADS
Loads shall be distributed as specified in Section 3 of AASHTO except as clarified or modified in these guidelines. Truck wheel loads are delivered to a flexible support through compressible tires, which make it very difficult to define the area of the bridge deck significantly influenced. Computerized grid systems and finite element programs can come close to reality, but they are complicated to apply and are limited by mesh or element size and by the accuracy with which the mechanical properties of the composite materials can be modeled. These two- or three dimensional problems are reduced to one dimension through various empirical distribution factors given in the AASHTO Standard Specifications. These distribution factors have been derived from research involving physical testing and/or computerized parameter studies. In order to simplify the design procedure, the number of variables was reduced to a minimum consistent with safety and reasonable economy, according to the judgment of the AASHTO Subcommittee on Bridges and Struct